Patent Publication Number: US-2016223413-A1

Title: Stress sensor and fabrication method for the same

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a continuation application (CA) of PCT Application No. PCT/JP2014/067984, filed on Jul. 4, 2014, which claims priority to Japan Patent Application No. P2013-140307 filed on Jul. 4, 2013 and is based upon and claims the benefit of priority from prior Japanese Patent Applications P2013-140307 filed on Jul. 4, 2013 and PCT Application No. PCT/JP2014/067984, filed on Jul. 4, 2014, the entire contents of each of which are incorporated herein by reference. 
    
    
     FIELD 
     The embodiment described herein relates to a stress sensor and a fabrication method for the stress sensor. 
     BACKGROUND 
     There have been developed sensors provided with various functions as detection devices having excellent performance which is alternative to or exceeds human&#39;s five senses. Such sensors detect natural phenomena, e.g. motion, optics, and temperatures, a mechanical, electromagnetical, thermal, and acoustical characteristics of artifacts, or space information or time information indicated by such characteristics, in order to control equipment. Thereby, more precise and accurate motions, and simpler and more easy-to-use operation methods can also be realized, and therefore higher effects to reduce power requirements can also be produced. Novel efforts using such sensors in various fields, e.g. factories, medical care/health care, transport facilities, construction industries, agricultural facilities, and environmental management, etc. have already been started. 
     It is expected that a variety of detection objects will be increased so as to support to various scenes, in addition to achievement of further improved performance for already-existing sensors, as a requirement in the sensors, in the future. 
     For example, there are listed variously-used sensors, e.g., acceleration sensors gyroscope sensors, touch sensors, Hall sensors, tilt sensors, grip sensors, pulse wave sensors, etc., and are also listed variously-used sensors, e.g., image sensors, pressure sensors, illuminance sensors, proximity sensors, pyroelectric sensors, humidity sensors, UV sensors, Infrared Data Association (IrDA), X ray sensors, odor sensors, etc., as examples of sensors for the purpose of detecting environments. 
     As conventional technologies associated with detection of mechanical forces, stress sensors, strain sensors, pressure sensors, etc. are listed, and are classified as follows: Thus, piezoresistive effect elements using metallic detect strain by converting an increase and decrease in an electric resistance due to metallic expansion and contraction into voltage. Since the piezoresistive effect element formed using metal uses the expansion and contraction phenomenon, a spatial resolution thereof is lower and an operational temperature range thereof is smaller. On the other hand, a detection principle of piezoresistive effect elements using a semiconductor is the same as that of the metaled piezoresistive effect elements. In the piezoresistive effect elements using the semiconductor, a silicon is processed into diaphragm structure, and thereby can sensitively detect a strain due to a pressure of a portion of which the layer thickness is thinner. Similarly, since the piezoresistive effect element using the semiconductor uses the expansion and contraction phenomenon, a spatial resolution thereof is lower and an operational temperature range thereof is smaller. Moreover, the piezoresistive effect elements using the semiconductor is mechanically weak. Since piezoelectric effect elements using dielectrics uses a piezoelectric effect, such piezoelectric effect elements using dielectrics can detect a dynamic stress (acceleration, vibration, etc.), but are not suitable for detection of static stress. 
     On the other hand, magnetostrictive stress sensors using an inverse magnetostrictive effect has a principle of detecting strain from a relationship between magnetization and stress characteristics as the whole ferromagnetic material, and uses a phenomenon in which the magnetization changes due to strain applied to the ferromagnetic material. However, a spatial resolution of the magnetostrictive stress sensor using the inverse magnetostrictive effect is lower. 
     It is difficult to detect a local stress using a high spatial resolution in each above-mentioned method. 
     For example, garnet has been known as insulator materials showing ferromagnetic materials at a room temperature. If garnet is fabricated by using a liquid phase epitaxy, growth-induced magnetic anisotropy which is a phenomenon peculiar to the fabricating method appears. It has been known that the magnetic anisotropy will occur since ordering of a rare earth element spontaneously occurs during crystal growth by the growth-induced magnetic anisotropy, and thereby a vertical magnetization film can be obtained. Moreover, it has been known that such a growth-induced magnetic anisotropy can be reduced by an anneal process. 
     SUMMARY 
     In the embodiment, a magnetic material is used as a host material of the stress sensor. 
     The embodiment provides: a stress sensor which can detect a local stress or stress distribution with a convenience structure, and can obtain a high spatial resolution by using a stress response phenomenon of a single magnetic domain; and a fabrication method for such a stress sensor. 
     According to one aspect of the embodiment, there is provided a stress sensor comprising: a magnetic material; a stress applied portion on the magnetic material; a magnet disposed so as to be adjacent to the magnetic material; and a magnetic sensor disposed via the magnetic material so as to be opposed to the stress applied portion, wherein the magnetic sensor detects a magnetic flux emitted from a magnetic domain generated in the magnetic material by a local stress applied to the stress applied portion. 
     According to another aspect of the embodiment, there is provided a stress sensor comprising: a magnetic material; a stress applied portion of the magnetic material; a magnet disposed so as to be adjacent to the magnetic material; and a magnetic sensor disposed via the magnetic material so as to be opposed to the stress applied portion, wherein a magnetic flux emitted from a magnetic domain is detected by the magnetic sensor, and thereby displacement of a magnetic domain due to stress distribution is detected. 
     According to another aspect of the embodiment, there is provided a fabrication method for a stress sensor comprising: preparing a magnetic material; disposing a magnet so as to be adjacent to the magnetic material; and disposing a magnetic sensor via the magnetic material so as to be opposed to the stress applied portion on the magnetic material, wherein the magnetic sensor is a magnetic sensor configured to detect a magnetic flux emitted from a magnetic domain generated in the magnetic material due to a local stress applied to the stress applied portion, wherein a step of fabricating the magnetic sensor comprises: forming an insulating layer on the magnetic material; pattern-forming a bismuth electrode layer on the insulating layer; pattern-forming a pad electrode on the bismuth electrode layer; forming a passivation film on the pad electrode; forming an aperture to the pad electrode in the passivation film; and connecting a bonding wire to the aperture. 
     According to another aspect of the embodiment, there is provided a fabrication method for a stress sensor comprising: preparing a magnetic material; disposing a magnet so as to be adjacent to the magnetic material; and disposing a magnetic sensor via the magnetic material so as to be opposed to the stress applied portion on the magnetic material, wherein the magnetic sensor is a magnetic sensor configured to detect displacement of a magnetic domain due to stress distribution by detecting a magnetic flux emitted from the magnetic domain, wherein a step of fabricating the magnetic sensor comprises: forming an insulating layer on the magnetic material; 
     pattern-forming a bismuth electrode layer on the insulating layer; pattern-forming a pad electrode on the bismuth electrode layer; forming a passivation film on the pad electrode; forming an aperture to the pad electrode in the passivation film; and connecting a bonding wire to the aperture. 
     According to the embodiment, there can be provided a stress sensor which can detect a local stress or stress distribution with a convenience structure, and can obtain a high spatial resolution by using a stress response phenomenon of a single magnetic domain; and a fabrication method for such a stress sensor. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1A  is a schematic cross-sectional structure diagram of a magnetic material having magnetization M to which an external magnetic field Hex higher than a saturation magnetic field Hs is applied, in an operational principle of a stress sensor according to an embodiment. 
         FIG. 1B  is a schematic cross-sectional structure diagram of the magnetic material in which a stress-induced anisotropic magnetic field H A  is generated, and a magnetic bubble is generated by applying a local stress to the magnetic material with a tungsten needle, in the operational principle of the stress sensor according to the embodiment. 
         FIG. 1C  is a schematic cross-sectional structure diagram of the magnetic material in a (volatility) state where a magnetizing direction due to the stress-induced anisotropic magnetic field H A  is not stored after the tungsten needle is released, in the operational principle of the stress sensor according to the embodiment. 
         FIG. 1D  is a schematic diagram of a surface state of the magnetic material corresponding to  FIG. 1A , in the operational principle of the stress sensor according to the embodiment. 
         FIG. 1E  is a schematic diagram of a surface state of the magnetic material corresponding to  FIG. 1B , in the operational principle of the stress sensor according to the embodiment. 
         FIG. 1F  is a schematic diagram of a surface state of the magnetic material corresponding to  FIG. 10 , in the operational principle of the stress sensor according to the embodiment. 
         FIG. 2A  is a schematic cross-sectional structure diagram of the magnetic material having magnetization M to which the external magnetic field Hex of the same degree as the saturation magnetic field Hs is applied, in the operational principle of the stress sensor according to the embodiment. 
         FIG. 2B  is a schematic cross-sectional structure diagram of the magnetic material in which the stress-induced anisotropic magnetic field H A  is generated, and the magnetic bubble is generated by applying the local stress to the magnetic material with the tungsten needle, in the operational principle of the stress sensor according to the embodiment. 
         FIG. 2C  is a schematic cross-sectional structure diagram of the magnetic material in a (nonvolatile) state where the magnetizing direction which is reversed due to the stress-induced anisotropic magnetic field H A  is stored after the tungsten needle is released, in the operational principle of the stress sensor according to the embodiment. 
         FIG. 2D  is a schematic diagram of a surface state of the magnetic material corresponding to  FIG. 2A , in the operational principle of the stress sensor according to the embodiment. 
         FIG. 2E  is a schematic diagram of a surface state of the magnetic material corresponding to  FIG. 2B , in the operational principle of the stress sensor according to the embodiment. 
         FIG. 2F  is a schematic diagram of a surface state of the magnetic material corresponding to  FIG. 2C , in the operational principle of the stress sensor according to the embodiment. 
         FIG. 3A  is a surface view observed from a magnetooptical microscope image of the magnetic material in which the magnetization M is generated by applying the external magnetic field Hex which is equal to the saturation magnetic field Hs thereto (before the tungsten needle is contacted), in an experimental example of the stress sensor according to the embodiment. 
         FIG. 3B  is a surface view observed from the magnetooptical microscope image of the magnetic material in which the stress-induced anisotropic magnetic field H A  is generated, and the magnetic bubble is generated by applying the local stress to the magnetic material with the tungsten needle, in the experimental example of the stress sensor according to the embodiment. 
         FIG. 3C  is a surface view observed from the magnetooptical microscope image of the magnetic material in a (nonvolatile) state where the magnetizing direction which is reversed due to the stress-induced anisotropic magnetic field H A  is stored after the tungsten needle is released, in the experimental example of the stress sensor according to the embodiment. 
         FIG. 4A  is a schematic cross-sectional structure diagram of the magnetic material having the magnetization M on which the external magnetic field Hex is applied, in an explanatory diagram of the local stress detected by the stress sensor according to the embodiment. 
         FIG. 4B  is a schematic cross-sectional structure diagram of a configuration of the magnetic material in which the stress-induced anisotropic magnetic field H A  is generated by applying the local stress to the magnetic material with the tungsten needle in a state of applying the external magnetic field Hex thereto, and a magnetic sensor disposed at a back surface side of the magnetic material opposite to the surface contacted by the tungsten needle, in the explanatory diagram of the local stress detected by the stress sensor according to the embodiment. 
         FIG. 4C  is a schematic cross-sectional structure diagram of the stress sensor on which a magnetic substance thin film and a protective film are formed at a front surface side of the magnetic material, and a magnetic sensor is disposed at a back surface side of the magnetic material, in the explanatory diagram of the local stress detected by the stress sensor according to the embodiment. 
         FIG. 5A  is a surface view (before the tungsten needle is contacted) observed from a magnetooptical microscope image of the magnetic material in which the magnetic bubble is generated by applying a magnetic field for generating magnetic bubble as the external magnetic field Hex thereto, in the experimental example of the stress sensor according to the embodiment. 
         FIG. 5B  is a surface view observed from the magnetooptical microscope image of the magnetic material in a state where the local stress is applied to the magnetic material with the tungsten needle (1.15 mN), in the experimental example of the stress sensor according to the embodiment. 
         FIG. 5C  is a difference image between  FIG. 5A  and  FIG. 5B , in the experimental example of the stress sensor according to the embodiment. 
         FIG. 6  is a schematic cross-sectional structure diagram showing the stress sensor according to the embodiment. 
         FIG. 7  is a schematic cross-sectional structure diagram showing a stress sensor according to a modified example 1 of the embodiment. 
         FIG. 8  is a schematic cross-sectional structure diagram showing a stress sensor according to a modified example 2 of the embodiment. 
         FIG. 9  is a schematic cross-sectional structure diagram showing a stress sensor according to a modified example 3 of the embodiment. 
         FIG. 10  is a schematic cross-sectional structure diagram showing a stress sensor according to a modified example 4 of the embodiment. 
         FIG. 11  is a schematic cross-sectional structure diagram showing a stress sensor according to a modified example 5 of the embodiment. 
         FIG. 12  is a schematic cross-sectional structure diagram showing a stress sensor according to a modified example 6 of the embodiment. 
         FIG. 13A  is a schematic planar pattern configuration diagram showing a stress sensor according to a modified example 7 of the embodiment. 
         FIG. 13B  is a schematic cross-sectional structure diagram taken in the line I-I of  FIG. 13A . 
         FIG. 14A  is a schematic planar pattern configuration diagram showing a stress distribution detecting apparatus to which the stress sensor according to the embodiment is applied. 
         FIG. 14B  is a schematic cross-sectional structure diagram taken in the line II-II of  FIG. 14A . 
         FIG. 15A  shows a relationship (magnetizing curve) the external magnetic field Hex of the magnetic material applied to the stress sensor according to the embodiment, and the magnetization M [an example before an anneal process]. 
         FIG. 15B  shows a relationship (magnetizing curve) the external magnetic field Hex of the magnetic material applied to the stress sensor according to the embodiment, and the magnetization M [an example of being annealed at 1150 degrees C.]. 
         FIG. 15C  shows a relationship (magnetizing curve) the external magnetic field Hex of the magnetic material applied to the stress sensor according to the embodiment, and the magnetization M [an example of being annealed at 1200 degrees C.]. 
         FIG. 16  shows annealing temperature dependency between the saturation magnetic field Hs and a saturation magnetic field ratio (the quotient of the saturation magnetic field H s , ⊥ in an out-of-plane direction divided by the saturation magnetic field H s , ∥ in an in-plane direction), in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 17A  is a diagram showing the magnetic field dependency observed from a magnetooptical microscope image to be corresponded with the magnetizing curve (relationship between the external magnetic field Hex and the magnetization M), in the magnetic material applied to the stress sensor according to the embodiment [an example before an anneal process]. 
         FIG. 17B  is a diagram showing the magnetic field dependency observed from a magnetooptical microscope image to be corresponded with the magnetizing curve (relationship between the external magnetic field Hex and the magnetization M), in the magnetic material applied to the stress sensor according to the embodiment [an example of being annealed at 1200 degrees C.]. 
         FIG. 18  is a schematic configuration diagram showing a magnetooptical microscope measuring system made by combining a local stress control system, in an instrumentation system of the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 19A  is a schematic cross-sectional structure diagram (the magnetooptical microscope image corresponds to  FIG. 3A ) at the time when an annealing sample at an annealing temperature of 1200 degrees C. is applied to the saturation magnetic field (Hex=H s =560 (Oe)), in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 19B  is a schematic cross-sectional structure diagram (the magnetooptical microscope image corresponds to  FIG. 3B ) showing the magnetic material in which the stress-induced anisotropic magnetic field H A  is generated by applying the local stress to the magnetic material with the tungsten needle, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 19C  is a schematic cross-sectional structure diagram (the magnetooptical microscope image corresponds to  FIG. 3C ) showing the magnetic material in a (nonvolatile) state where the magnetizing direction which is reversed due to the stress-induced anisotropic magnetic field H A  is stored after releasing the tungsten needle, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 20A  is a surface view observed from a magnetooptical microscope image of the magnetic material in a state where the external magnetic field Hex is not applied thereto (Hex=0 (Oe)) (before the tungsten needle is contacted), in an experimental example of the stress sensor according to the embodiment. 
         FIG. 20B  is a surface view observed from the magnetooptical microscope image of the magnetic material in a state where the local stress is applied to the magnetic material with the tungsten needle (7.79 mN), in the experimental example of the stress sensor according to the embodiment. 
         FIG. 20C  shows a difference image between  FIG. 20A  and  FIG. 20B . 
         FIG. 21A  is a surface view observed from a magnetooptical microscope image of the magnetic material in which a magnetic bubble domain is generated by applying a magnetic field for generating magnetic bubble domain (Hex=280 (Oe)) as the external magnetic field Hex thereto (before the tungsten needle is contacted), in the experimental example of the stress sensor according to the embodiment. 
         FIG. 21B  is a surface view observed from the magnetooptical microscope image of the magnetic material in a state where the local stress is applied to the magnetic material with the tungsten needle (1.15 mN), in the experimental example of the stress sensor according to the embodiment. 
         FIG. 21C  shows a difference image between  FIG. 21A  and  FIG. 21B . 
         FIG. 22A  is a diagram showing the magnetic field dependency observed from a magnetooptical microscope image to be corresponded with the magnetizing curve (relationship between the external magnetic field Hex and the magnetization M), in the magnetic material applied to the stress sensor according to the embodiment [an example of being annealed at 1200 degrees C.] (corresponding to  FIG. 17B ). 
         FIG. 22B  is a diagram showing a relationship between the external magnetic field Hex and threshold force f, in a result of examining a relationship between a magnetic domain motion and a threshold load, while changing magnetic domain structure by applying an external magnetic field Hex in perpendicular-to-plane direction thereto, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 23A  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=0 (Oe), before the tungsten needle is contacted thereto, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 23B  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=0 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 23C  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=0 (Oe), when applying the threshold force f=3.14 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 23D  is surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=0 (Oe), when applying the threshold force f=6.70 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 23E  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=0 (Oe), when applying the threshold force f=7.79 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 23F  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=0 (Oe), when applying the threshold force f=6.30 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 23G  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=0 (Oe), when applying the threshold force f=2.86 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 23H  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=0 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 23I  is a diagram showing a surface view after releasing the tungsten needle. 
         FIG. 24A  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), before the tungsten needle is contacted thereto, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 24B  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 24C  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), when applying the threshold force f=2.92 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 24D  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), when applying the threshold force f=4.32 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 24E  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), when applying the threshold force f=5.60 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 24F  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), when applying the threshold force f=4.36 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 24G  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), when applying the threshold force f=2.94 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 24H  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 24I  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), after the tungsten needle is released therefrom, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 25A  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), before the tungsten needle is contacted thereto, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 25B  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 25C  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), when applying the threshold force f=1.36 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 25D  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), when applying the threshold force f=3.12 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 25E  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), when applying the threshold force f=4.28 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 25F  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), when applying the threshold force f=2.83 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 25G  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), when applying the threshold force f=1.41 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 25H  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 25I  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), after the tungsten needle is released therefrom, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 26A  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), before the tungsten needle is contacted thereto, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 26B  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 26C  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), when applying the threshold force f=2.19 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 26D  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), when applying the threshold force f=2.59 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 26E  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), when applying the threshold force f=3.43 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 26F  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), when applying the threshold force f=2.57 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 26G  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), when applying the threshold force f=1.96 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 26H  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 26I  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), after the tungsten needle is released therefrom, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 27A  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=280 (Oe), before the tungsten needle is contacted thereto, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 27B  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=280 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 27C  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=280 (Oe), when applying the threshold force f=1.15 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 27D  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=280 (Oe), when applying the threshold force f=5.10 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 27E  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=280 (Oe), when applying the threshold force f=9.92 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 27F  is a surface view diagram when applying the threshold force f=5.40 mN. 
         FIG. 27G  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=280 (Oe), when applying the threshold force f=0.34 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 27H  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=280 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 27I  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=280 (Oe), after the tungsten needle is released therefrom, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 28A  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), before the tungsten needle is contacted thereto, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 28B  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 28C  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), when applying the threshold force f=1.22 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 28D  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), when applying the threshold force f=4.96 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 28E  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), when applying the threshold force f=9.90 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 28F  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), when applying the threshold force f=5.24 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 28G  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), when applying the threshold force f=1.24 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 28H  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 28I  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), after the tungsten needle is released therefrom, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 29A  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe), before the tungsten needle is contacted thereto, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 29B  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 29C  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe) when applying the threshold force f=1.18 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 29D  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe), when applying the threshold force f=4.96 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 29E  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe), when applying the threshold force f=2.56 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 29F  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe), when applying the threshold force f=1.71 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 29G  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe), when applying the threshold force f=1.13 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 29H  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 29I  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe), after the tungsten needle is released therefrom, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 30A  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), before the tungsten needle is contacted thereto, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 30B  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 30C  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), when applying the threshold force f=1.24 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 30D  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), when applying the threshold force f=2.49 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 30E  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), when applying the threshold force f=3.75 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 30F  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), when applying the threshold force f=2.22 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 30G  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), when applying the threshold force f=1.40 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 30H  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 30I  is a surface view observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), after the tungsten needle is released therefrom, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 31A  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=0 (Oe), before the tungsten needle is contacted thereto, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 31B  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=0 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 31C  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=0 (Oe), when applying the threshold force f=3.14 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 31D  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=0 (Oe), when applying the threshold force f=6.70 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 31E  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=0 (Oe), when applying the threshold force f=7.79 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 31F  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=0 (Oe), when applying the threshold force f=6.30 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 31G  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=0 (Oe), when applying the threshold force f=2.86 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 31H  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=0 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 31I  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=0 (Oe), after the tungsten needle is released therefrom, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 32A  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), before the tungsten needle is contacted thereto, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 32B  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 32C  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), when applying the threshold force f=2.92 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 32D  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), when applying the threshold force f=4.32 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 32E  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), when applying the threshold force f=5.60 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 32F  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), when applying the threshold force f=4.36 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 32G  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), when applying the threshold force f=2.94 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 32H  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 32I  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), after the tungsten needle is released therefrom, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 33A  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), before the tungsten needle is contacted thereto, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 33B  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 33C  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), when applying the threshold force f=1.36 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 33D  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), when applying the threshold force f=3.12 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 33E  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), when applying the threshold force f=4.28 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 33F  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), when applying the threshold force f=2.83 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 33G  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), when applying the threshold force f=1.41 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 33H  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 33I  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), after the tungsten needle is released therefrom, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 34A  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), before the tungsten needle is contacted thereto, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 34B  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 34C  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), when applying the threshold force f=2.19 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 34D  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), when applying the threshold force f=2.59 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 34E  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), when applying the threshold force f=3.43 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 34F  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), when applying the threshold force f=2.57 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 34G  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), when applying the threshold force f=1.96 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 34H  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 34I  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), after the tungsten needle is released therefrom, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 35A  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=280 (Oe), before the tungsten needle is contacted thereto, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 35B  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=280 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 35C  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=280 (Oe), when applying the threshold force f=1.15 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 35D  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=280 (Oe), when applying the threshold force f=5.10 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 35E  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=280 (Oe), when applying the threshold force f=9.92 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 35F  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=280 (Oe), when applying the threshold force f=5.40 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 35G  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=280 (Oe), when applying the threshold force f=0.34 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 35H  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=280 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 35I  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=280 (Oe), after the tungsten needle is released therefrom, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 36A  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), before the tungsten needle is contacted thereto, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 36B  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 36C  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), when applying the threshold force f=1.22 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 36D  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), when applying the threshold force f=4.96 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 36E  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), when applying the threshold force f=9.90 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 36F  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), when applying the threshold force f=5.24 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 36G  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), when applying the threshold force f=1.24 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 36H  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 36I  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), after the tungsten needle is released therefrom, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 37A  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe), before the tungsten needle is contacted thereto, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 37B  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 37C  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe), when applying the threshold force f=1.18 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 37D  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe), when applying the threshold force f=4.96 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 37E  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe), when applying the threshold force f=2.56 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 37F  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe), when applying the threshold force f=1.71 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 37G  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe), when applying the threshold force f=1.13 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 37H  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 37I  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe), after the tungsten needle is released therefrom, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 38A  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), before the tungsten needle is contacted thereto, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 38B  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 38C  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), when applying the threshold force f=1.24 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 38D  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), when applying the threshold force f=2.49 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 38E  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), when applying the threshold force f=3.75 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 38F  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), when applying the threshold force f=2.22 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 38G  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), when applying the threshold force f=1.40 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 38H  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 38I  is a superimposed image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), after the tungsten needle is released therefrom, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 39A  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=0 (Oe), before the tungsten needle is contacted thereto, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 39B  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=0 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 39C  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=0 (Oe), when applying the threshold force f=3.14 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 39D  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=0 (Oe), when applying the threshold force f=6.70 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 39E  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=0 (Oe), when applying the threshold force f=7.79 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 39F  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=0 (Oe), when applying the threshold force f=6.30 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 39G  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=0 (Oe), when applying the threshold force f=2.86 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 39H  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=0 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 39I  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=0 (Oe), after the tungsten needle is released therefrom, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 40A  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), before the tungsten needle is contacted thereto, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 40B  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 40C  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), when applying the threshold force f=2.92 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 40D  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), when applying the threshold force f=4.32 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 40E  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), when applying the threshold force f=5.60 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 40F  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), when applying the threshold force f=4.36 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 40G  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), when applying the threshold force f=2.94 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 40H  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 40I  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=70 (Oe), after the tungsten needle is released therefrom, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 41A  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), before the tungsten needle is contacted thereto, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 41B  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 41C  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), when applying the threshold force f=1.36 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 41D  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), when applying the threshold force f=3.12 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 41E  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), when applying the threshold force f=4.28 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 41F  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), when applying the threshold force f=2.83 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 41G  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), when applying the threshold force f=1.41 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 41H  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 41I  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=130 (Oe), after the tungsten needle is released therefrom, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 42A  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), before the tungsten needle is contacted thereto, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 42B  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 42C  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), when applying the threshold force f=2.19 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 42D  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), when applying the threshold force f=2.59 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 42E  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), when applying the threshold force f=3.43 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 42F  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), when applying the threshold force f=2.57 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 42G  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), when applying the threshold force f=1.96 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 42H  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 42I  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=200 (Oe), after the tungsten needle is released therefrom, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 43A  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=280 (Oe), before the tungsten needle is contacted thereto, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 43B  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=280 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 43C  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=280 (Oe), when applying the threshold force f=1.15 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 43D  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=280 (Oe), when applying the threshold force f=5.10 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 43E  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=280 (Oe), when applying the threshold force f=9.92 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 43F  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=280 (Oe), when applying the threshold force f=5.40 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 43G  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=280 (Oe), when applying the threshold force f=0.34 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 43H  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=280 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 43I  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=280 (Oe), after the tungsten needle is released therefrom, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 44A  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), before the tungsten needle is contacted thereto, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 44B  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 44C  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), when applying the threshold force f=1.22 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 44D  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), when applying the threshold force f=4.96 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 44E  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), when applying the threshold force f=9.90 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 44F  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), when applying the threshold force f=5.24 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 44G  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), when applying the threshold force f=1.24 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 44H  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 44I  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=390 (Oe), after the tungsten needle is released therefrom, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 45A  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe), before the tungsten needle is contacted thereto, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 45B  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 45C  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe), when applying the threshold force f=1.18 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 45D  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe), when applying the threshold force f=4.96 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 45E  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe), when applying the threshold force f=2.56 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 45F  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe), when applying the threshold force f=1.71 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 45G  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe), when applying the threshold force f=1.13 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 45H  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 45I  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=500 (Oe), after the tungsten needle is released therefrom, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 46A  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), before the tungsten needle is contacted thereto, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 46B  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 46C  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), when applying the threshold force f=1.24 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 46D  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), when applying the threshold force f=2.49 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 46E  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), when applying the threshold force f=3.75 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 46F  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), when applying the threshold force f=2.22 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 46G  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), when applying the threshold force f=1.40 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 46H  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), when applying the threshold force f=0.00 mN, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 46I  is a difference image before and after a displacement of the magnetic domain observed from the magnetooptical microscope image of the magnetic material in the case of the external magnetic field Hex=560 (Oe), after the tungsten needle is released therefrom, in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 47A  shows annealing temperature dependency (diagram corresponding to  FIG. 16 ) of between the saturation magnetic field Hs and a saturation magnetic field ratio (the quotient of the saturation magnetic field H s , ⊥ in an out-of-plane direction divided by the saturation magnetic field H s , ∥ in an in-plane direction), in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 47B  shows annealing temperature dependency between the external magnetic field Hex (Oe) and the threshold force f (mN), showing an aspect that a threshold load of the magnetic domain motion is reduced by increasing the annealing temperature (reduction of magnetic anisotropy), in the magnetic material applied to the stress sensor according to the embodiment. 
         FIG. 48A  is a diagram explaining magnet disposition in a local magnetic field generating apparatus, showing a configuration example that the magnet is disposed on a supporting base so as to surround the magnetic material. 
         FIG. 48B  is a diagram explaining the magnet disposition in the local magnetic field generating apparatus, showing a configuration example that the magnet is disposed on the magnetic material. 
         FIG. 49  is a schematic diagram showing a relationship between a magnetic sensor output and a local stress (or stress-induced anisotropic magnetic field), in the stress sensor according to the embodiment configured to using a Hall element as the magnetic sensor. 
         FIG. 50A  is a schematic diagram showing the magnetic sensor corresponding to the point A shown in  FIG. 49 , for explaining an aspect that an area of the magnetic bubble which occupies directly under an effective region of the magnetic sensor gradually increases by increasing the stress. 
         FIG. 50B  is a schematic diagram showing a magnetic bubble BB 1  corresponding to the point B shown in  FIG. 49 . 
         FIG. 50C  is a schematic diagram showing a magnetic bubble BB 2  corresponding to the point C shown in  FIG. 49 . 
         FIG. 50D  is a schematic diagram showing a magnetic bubble BB 3  corresponding to the point D shown in  FIG. 49 . 
         FIG. 51  is a schematic planar pattern configuration diagram showing a Hall element applicable to the magnetic sensor of the stress sensor according to the embodiment. 
         FIG. 52  is a schematic bird&#39;s-eye view configuration diagram showing the Hall element applicable to the magnetic sensor of the stress sensor according to the embodiment. 
         FIG. 53  shows a surface optical micrograph of one element portion of the Hall element applicable to the magnetic sensor of the stress sensor according to the embodiment. 
         FIG. 54  is a schematic cross-sectional structure diagram taken in the line of  FIG. 53 , showing the Hall element applicable to the magnetic sensor of the stress sensor according to the embodiment. 
         FIG. 55  is a scanning electron microscope (SEM) photograph of a surface of the center portion of hole crossbar of the Hall element and an explanatory diagram of the center portion of hole crossbar applicable to the magnetic sensor of the stress sensor according to the embodiment. 
         FIG. 56  is an explanatory diagram of a Hall probe operation droved by an applied magnetic field B, in the magnetic sensor to which the Hall element is applied, showing a relationship between an output hall voltage V H  (μV) and an output magnetic field B O , and the applied magnetic field B. 
         FIG. 57A  is a diagram showing an example of a bubble domain DM (−) of the garnet magnetic material existing directly under the center portion of hole crossbar, in the magnetic sensor to which the Hall element is applied. 
         FIG. 57B  is a diagram showing an example of a bubble domain DM (+) of the garnet magnetic material existing directly under the center portion of hole crossbar, in the magnetic sensor to which the Hall element is applied. 
         FIG. 58A  is a diagram showing an example of sizes of each portion of a magnetic recording medium (domain width d, and thickness t of the magnetic recording medium), in the magnetic sensor to which the Hall element is applied. 
         FIG. 58B  shows a characteristic example showing a relationship between a vertical magnetic flux density B Z  (mT) and the height Z of the magnetic field emitted from the magnetic recording medium using the domain width d as a parameter, in the magnetic sensor to which the Hall element is applied. 
         FIG. 59A  is a schematic cross-sectional structure diagram which shows forming an insulating layer after forming an alignment electrode layer on the magnetic recording medium, in an explanatory diagram of a fabrication method for the magnetic sensor to which the Hall element is applied. 
         FIG. 59B  is a schematic cross-sectional structure diagram which shows pattern-forming a bismuth (Bi) electrode layer on the insulating layer, in the explanatory diagram of the fabrication method for the magnetic sensor to which the Hall element is applied. 
         FIG. 59C  is a schematic cross-sectional structure diagram which shows forming a passivation film on the entire surface after pattern-forming a pad electrode in contact with the Bi electrode layer, in the explanatory diagram of the fabrication method for the magnetic sensor to which the Hall element is applied. 
         FIG. 59D  is a schematic cross-sectional structure diagram which shows forming a contact hole into the pad electrode, in the explanatory diagram of the fabrication method for the magnetic sensor to which the Hall element is applied. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Next, a certain embodiment will be described with reference to drawings. In the description of the following drawings, the identical or similar reference numeral is attached to the identical or similar part. However, it should be noted that the drawings are schematic and the relation between thickness and the plane size and the ratio of the thickness of each component part differs from an actual thing. Therefore, detailed thickness and size should be determined in consideration of the following explanation. 
     Of course, the part from which the relation and ratio of a mutual size differ also in mutually drawings is included. Moreover, the embodiment described hereinafter merely exemplifies the device and method for materializing the technical idea; and the embodiment does not specify the material, shape, structure, placement, etc. of each component part as the following. The embodiment may be changed without departing from the spirit or scope of claims. 
     The stress sensor according to the embodiment includes a local stress detecting apparatus and a stress distribution detecting apparatus. 
     The local stress detecting apparatus can detect a local stress by generating a magnetic domain by applying the local stress to the magnetic material. Moreover, the stress distribution detecting apparatus can detect stress distribution by detecting magnetic field distribution with a plurality of magnetic field detecting elements (magnetic sensors), by displacing the magnetic domain by applying stress to the magnetic material. 
     The stress sensor according to the embodiment can detect the local stress with a convenience structure made by combining the magnetic material and the magnetic sensor. The magnetic domain width is dependent on the magnetic materials, and therefore a spatial resolution of the local magnetic field can easily be highly improved by selection of the magnetic materials. 
     (Generation of Local Magnetic Field) 
     In an operational principle of a stress sensor according to the embodiment,  FIG. 1A  shows a schematic cross-sectional structure of a magnetic material  10  having magnetization M to which an external magnetic field Hex higher than a saturation magnetic field Hs is applied. Moreover,  FIG. 2B  shows a schematic cross-sectional structure of the magnetic material  10  in which the stress-induced anisotropic magnetic field H A  is generated, and the magnetic bubble BUB is generated by applying the local stress to the magnetic material with the tungsten needle  40 . Moreover,  FIG. 10  shows a schematic cross-sectional structure of the magnetic material  10  in a (volatility) state where a magnetizing direction due to the stress-induced anisotropic magnetic field H A  is not stored after the tungsten needle  40  is released. Furthermore,  FIG. 1D  is a schematic diagram of a surface state of the magnetic material  10  corresponding to  FIG. 1A ,  FIG. 1E  is a schematic diagram of a surface state of the magnetic material  10  corresponding to  FIG. 1B , and  FIG. 1F  is a schematic diagram of a surface state of the magnetic material  10  corresponding to  FIG. 10 . 
     Moreover, in the operational principle of the stress sensor according to the embodiment,  FIG. 2A  shows a schematic cross-sectional structure of the magnetic material  10  having magnetization M to which the external magnetic field Hex of the same degree as the saturation magnetic field Hs is applied. Moreover,  FIG. 2B  shows a schematic cross-sectional structure of the magnetic material  10  in which the stress-induced anisotropic magnetic field H A  is generated, and the magnetic bubble BUB is generated by applying the local stress to the magnetic material  10  with the tungsten needle  40 . Moreover,  FIG. 2C  shows a schematic cross-sectional structure of the magnetic material  10  in a (nonvolatile) state where the magnetizing direction which is reversed due to the stress-induced anisotropic magnetic field H A  is stored after the tungsten needle  40  is released. Furthermore,  FIG. 2D  is a schematic diagram of a surface state of the magnetic material  10  corresponding to  FIG. 2A ,  FIG. 2E  is a schematic diagram of a surface state of the magnetic material  10  corresponding to  FIG. 2B , and  FIG. 2F  is a schematic diagram of a surface state of the magnetic material  10  corresponding to  FIG. 2C . 
     In an experimental example of the stress sensor according to the embodiment,  FIG. 3A  is a surface view observed from a magnetooptical microscope image of the magnetic material  10  in which the magnetization M is generated by applying the external magnetic field Hex which is equal to the saturation magnetic field Hs thereon (before the tungsten needle  40  is contacted). Moreover,  FIG. 3B  shows a surface view observed from a magnetooptical microscope image of the magnetic material  10  in which the stress-induced anisotropic magnetic field H A  is generated, and the magnetic bubble BUB is generated by applying the local stress to the magnetic material  10  with the tungsten needle  40 . Moreover,  FIG. 3C  shows a surface view observed from a magnetooptical microscope image of the magnetic material  10  in a (nonvolatile) state where the magnetizing (M A ) direction which is reversed due to the stress-induced anisotropic magnetic field H A  is stored after the tungsten needle  40  is released. 
     In the stress sensor according to the embodiment, the local stress is applied to the magnetic material  10 , then the stress-induced anisotropic magnetic field H A  is generated, and thereby the magnetic bubble BUB is generated. 
     In the stress sensor according to the embodiment, if the applied external magnetic field Hex is set up so as to be larger than the saturation magnetic field Hs, there can be achieved a volatile function in which the magnetizing direction is not stored therein after applying the stress, i.e., the local magnetic field can be turned on and off by turning on and off the stress. On the other hand, if the applied external magnetic field Hex is set up to the same degree as the saturation magnetic field Hs, the magnetizing direction is stored therein after applying the stress. Thus, there can be achieved a nonvolatile function in which the local magnetic field can be turned on by turning on the stress. Accordingly, the function can be changed with the external magnetic field Hex. Moreover, the diameter of the magnetic bubble, i.e., a spatial resolution of the local magnetic field, can be changed by selection of the materials of the magnetic material  10 . 
     (Detection of Local Stress) 
     In an explanatory diagram of the local stress detected by the stress sensor according to the embodiment,  FIG. 4A  shows a schematic cross-sectional structure of the magnetic material  10  having the magnetization M on which the external magnetic field Hex is applied.  FIG. 4B  shows a schematic cross-sectional structure of a configuration of the magnetic material  30  in which the stress-induced anisotropic magnetic field H A  is generated by applying the local stress to the magnetic material  10  with the tungsten needle  40  in a state of applying the external magnetic field Hex thereon and magnetization is saturated, and a magnetic sensor  30  disposed at a back surface side of the magnetic material  10  opposite to the contact surface (stress applied portion  402 ) contacted by the tungsten needle  40 .  FIG. 4C  is a schematic cross-sectional structure of the stress sensor  60  on which a magnet (magnetic substance thin film)  20  and a protective film  52  are formed at a front surface side of the magnetic material  10 , and a magnetic sensor  30  is disposed at a back surface side of the magnetic material  10 . In addition, the magnetic material  10  and the magnet (magnetic substance thin film)  20  may be insulated from each other by intervening an insulating layer therebetween. 
     According to the stress sensor according to the embodiment, as shown in  FIGS. 4A to 4C , the magnetic bubbles are generated, by applying the local stress to the magnetic material  10 , and thereby the magnetic sensor  30  can detect the local magnetic field. 
     In an experimental example of the stress sensor according to the embodiment,  FIG. 5A  is a surface view (before the tungsten needle  40  is contacted) observed from a magnetooptical microscope image of the magnetic material  10  in which the magnetic bubbles BUS are generated by applying a magnetic field for generating magnetic bubble as the external magnetic field Hex thereon. Moreover,  FIG. 5B  is a surface view observed from the magnetooptical microscope image of the magnetic material  10  in a state where the local stress (1.15 mN) is applied to the magnetic material  10  with the tungsten needle  40  (1.15 mN). Moreover,  FIG. 5C  shows a difference image between  FIG. 5A  and  FIG. 5B . Accordingly, displacement of the magnetic bubbles BUB: R 1 →B 1 , R 2 →B 2 , R 3 →B 3 , R 4 →B 4 , R 5 →B 5 , R 6 →B 6 , R 7 →B 7 , and R 8 →B 8  are observed by applying the local stress (1.15 mN) to the magnetic material  10 . 
     In the stress sensor according to the embodiment, as shown in  FIGS. 5A to 5C , when the magnetic field for generating magnetic bubble is applied, displacement of the magnetic bubbles due to the stress distribution are generated, by applying the local stress to the magnetic material  10 , and thereby the stress distribution can also be detected by a plurality of the magnetic sensors  30 . 
     (Configuration of Stress Sensor) 
     As shown in  FIG. 6 , the stress sensor according to the embodiment  60  includes: a magnetic material  10 ; a stress applied portion  40 P on the magnetic material  10 ; a magnet  20  disposed so as to be adjacent to the magnetic material  10 ; and a magnetic sensor  30  disposed via the magnetic material  10  so as to be opposed to the stress applied portion  40 P, wherein the magnetic sensor  30  detects a magnetic flux emitted from a magnetic domain generated in the magnetic material by a local stress applied to the stress applied portion  40 P. In the stress sensor according to the embodiment  60 , as an example, the tungsten needle  40  is used for applying the local stress to the stress applied portion  40 P in order to quantify the local stress, but, it is not limited to the tungsten needle  40  as a method of applying the local stress. In addition, it has been confirmed that the magnetic domain can be operated also by using a wooden toothpick, as other needlelike configurations, for example. Accordingly, this phenomenon can be used also for stress sensors used for not only the local stress sensor for very micro regions but also human interface purposes. 
     In the stress sensor according to the embodiment  60 , the magnet  20  and the magnetic sensor  30  respectively are disposed on the opposite to surfaces (i.e., the front side surface and the back side surface) of the magnetic material  10 , as shown in  FIG. 6 . 
     In the stress sensor according to the embodiment  60 , the saturation magnetic field is applied to the magnetic material  10  due to the magnet  20 , and the external magnetic field Hex due to the magnet  20  and the stress-induced anisotropic magnetic field H A  in the reverse direction are applied thereto with the local stress. Accordingly, the single magnetic bubble BUB is generated in the magnetic material  10 , and then the magnetic flux emitted from the magnetic bubble BUB is detected by the magnetic sensor  30 , and thereby the local stress can be detected. 
     Moreover, in the configuration shown in  FIG. 6 , physical damage to the magnetic sensor  30  is avoidable by disposing the magnetic sensor  30  so as to be opposed to the stress applied portion  402  via the magnetic material  10 . 
     Modified Example 1 
     In the stress sensor  60  according to a modified example 1 of the embodiment, both of the magnet  20  and the magnetic sensor  30  are disposed on one surface (e.g., back side surface) of the magnetic material  10 , as shown in  FIG. 7 . Other configurations are the same as those of the embodiment. 
     Modified Example 2 
     As shown in  FIG. 8 , a stress sensor  60  according to a modified example 2 of the embodiment includes: a magnetic material  10 ; a stress applied portion  40 P on the magnetic material  10 ; a magnetic sensor  30  disposed via the magnetic material  10  so as to be opposed to the stress applied portion  40 P; an insulating layer  50  disposed on the magnetic sensor  30 ; and a magnet  20  disposed on the insulating layer  50 . 
     In the stress sensor  60  according to the modified example 2 of the embodiment, both of the magnet  20  and the magnetic sensor  30  are disposed on one surface (e.g., front side surface) side of the magnetic material  10 , as shown in  FIG. 8 . The magnet  20  may be formed of a magnetic substance thin film etc. Other configurations are the same as those of the embodiment. 
     Modified Example 3 
     As shown in  FIG. 9 , a stress sensor  60  according to a modified example 3 of the embodiment includes: a magnetic material  10 ; a stress applied portion  40 P on the magnetic material  10 ; a magnetic sensor  30  disposed via the magnetic material  10  so as to be opposed to the stress applied portion  40 P; an insulating layer  50  disposed on the magnetic sensor  30 ; and a magnet  20  disposed on the insulating layer  50 . 
     In the stress sensor  60  according to the modified example 3 of the embodiment, as shown in  FIG. 9 , the magnet  20  and the magnetic material  10  respectively are disposed via the pattern-formed insulating layers  50  on one surface (e.g., back side surface) of the magnetic sensor  30 . The magnet  20  may be formed of a magnetic substance thin film etc. The magnetic material  10 , the magnet  20 , and the magnetic sensor  30  are integrated into one another by forming the magnet  20  with the magnetic substance thin film etc., and therefore it is preferred in view of applicability of device. Other configurations are the same as those of the embodiment. 
     Modified Example 4 
     As shown in  FIG. 10 , a stress sensor  60  according to a modified example 4 of the embodiment includes: a magnetic material  10 ; a stress applied portion  40 P on the magnetic material  10 ; a magnetic sensor  30  disposed via the magnetic material  10  so as to be opposed to the stress applied portion  40 P; an insulating layer  50  disposed on the magnetic sensor  30 ; and a magnet  20  disposed on the insulating layer  50 . 
     In the stress sensor  60  according to the modified example 4 of the embodiment, both of the magnet  20  and the magnetic material  10  are disposed on the insulating layer  50  formed on one surface (e.g., front side surface) of the magnetic sensor  30 , as shown in  FIG. 10 . The magnet  20  may be formed of a magnetic substance thin film etc. The magnetic material  10 , the magnet  20 , and the magnetic sensor  30  are integrated into one another by forming the magnet  20  with the magnetic substance thin film etc., and therefore it is preferred in view of applicability of device. Other configurations are the same as those of the embodiment. 
     Modified Example 5 
     As shown in  FIG. 11 , a stress sensor  60  according to a modified example 5 of the embodiment includes: a magnetic material  10 ; a stress applied portion  40 P on the magnetic material  10 ; a magnetic sensor  30  disposed via the magnetic material  10  so as to be opposed to the stress applied portion  40 P; and a magnet  20  disposed on the magnetic sensor  30 . 
     In the stress sensor  60  according to the modified example 5 of the embodiment, both of the magnet  20  and the magnetic material  10  are disposed on one surface (e.g., front side surface) of the magnetic sensor  30 , as shown in  FIG. 11 . The magnet  20  may be formed of a magnetic substance thin film etc. The magnetic material  10 , the magnet  20 , and the magnetic sensor  30  are integrated into one another by forming the magnet  20  with the magnetic substance thin film etc., and therefore it is preferred in view of applicability of device. Other configurations are the same as those of the embodiment. 
     Modified Example 6 
     As shown in  FIG. 12 , a stress sensor  60  according to a modified example 6 of the embodiment includes: a magnetic material  10 ; a stress applied portion  402  on the magnetic material  10 ; a magnetic sensor  30  disposed via the magnetic material  10  so as to be opposed to the stress applied portion  402 ; and a magnet  20  disposed on the magnetic material  10  so as to surround the magnetic sensor  30 . 
     In the stress sensor  60  according to the modified example 6 of the embodiment, both of the magnet  20  and the magnetic sensor  30  are disposed on one surface (e.g., front side surface) of the magnetic material  10 , as shown in  FIG. 12  via the insulating layer  50 . The magnet  20  may be formed of a magnetic substance thin film etc. Other configurations are the same as those of the embodiment. 
     Modified Example 7 
       FIG. 13A  shows a schematic planar pattern configuration of a stress sensor  60  according to a modified example 7 of the embodiment, and  FIG. 13B  shows a schematic cross-sectional structure taken in the line I-I of  FIG. 13A . 
     As shown in  FIGS. 13A and 13B , a stress sensor  60  according to a modified example 7 of the embodiment includes: a magnetic material  10 ; a plurality of stress applied portions  402  on the magnetic material  10 ; 
     a magnet  20  disposed so as to be adjacent to the magnetic material  10 ; and a plurality of magnetic sensors  30   1 ,  30   2 ,  30   3  disposed via the magnetic material  10  so as to be opposed to the plurality of the stress applied portions  40 P, wherein a magnetic flux emitted from a magnetic domain is detected by the plurality of the magnetic sensors  30   1 ,  30   2 ,  30   3 , and thereby displacement of the magnetic domain due to stress distribution is detected. 
     In the stress sensor  60  according to the modified example 7 of the embodiment, both of the magnet  20  and the plurality of the magnetic sensors  30   1 ,  30   2 ,  30   3  are disposed on one surface (e.g., front side surface) of the magnetic material  10 , as shown in  FIG. 13B  via the insulating layer  50 . The magnet  20  may be formed of a magnetic substance thin film etc. 
     In the stress sensor  60  according to the modified example 7 of the embodiment, a magnetic field for generating magnetic bubble is applied to the magnetic material  10  by the magnet  20 , and a stress-induced anisotropic magnetic field H A  is applied due to the stress distribution. Thus, displacement of the magnetic bubble is generated and then the magnetic flux emitted from the magnetic bubble is detected by the magnetic sensors  30   1 ,  30   2 ,  30   3 , and thereby the stress distribution can be detected. 
     Moreover, in the configuration shown in  FIG. 13 , physical damage to the magnetic sensors  30   1 ,  30   2 ,  30   3  is avoidable by disposing the magnetic sensors  30   1 ,  30   2 ,  30   3  so as to be opposed to the stress applied portion  40 P via the magnetic material  10 . 
     Modified Example 8 
       FIG. 14A  shows a schematic planar pattern configuration of a stress sensor  60  according to a modified example 8 of the embodiment, and  FIG. 14B  shows a schematic cross-sectional structure taken in the line II-II of  FIG. 14A . 
     As shown in  FIGS. 14A and 11B , a stress sensor  60  according to a modified example 8 of the embodiment includes: a magnetic material  10 ; a stress applied portion  40 P on the magnetic material  10 ; a magnet  20  disposed so as to be adjacent to the magnetic material  10 ; and a plurality of magnetic sensors  30   1 ,  30   2 ,  30   3 ,  30   11 ,  30   12 , . . . ,  30   1n  . . . ,  30   m1 ,  30   m2 , . . . ,  30   mn  (MS 11 , MS 12 , . . . , MS 1n , . . . , MS m1 , MS m2  . . . , MS mn ) disposed via the magnetic material  10  so as to be opposed to the stress applied portion  40 P, wherein a magnetic flux emitted from a magnetic domain is detected by the plurality of the magnetic sensors  30   1 ,  30   2 ,  30   3 ,  30   11 ,  30   12 , . . . ,  30   1n  . . . ,  30   m1 ,  30   m2 ,  30   mn , and thereby displacement of the magnetic domain due to stress distribution is detected. 
     In the stress sensor  60  according to the modified example 8 of the embodiment, both of the magnet  20  and the plurality of the magnetic sensors  30   1 ,  30   2 ,  30   3 ,  30   11 ,  30   12 , . . . ,  30   1n  . . . ,  30   m1 ,  30   m2 , . . . ,  30   mn  (MS 11 , MS 12 , . . . , MS 1n , . . . , MS m1 , MS m2 , . . . MS mn ) are disposed on one surface (e.g., front side surface) of the magnetic material  10 , as shown in  FIG. 14B  via the insulating layer  50 . The magnet  20  may be formed of a magnetic substance thin film etc. 
     In the stress sensor  60  according to the modified example 8 of the embodiment, a magnetic field for generating magnetic bubble is applied to the magnetic material  10  by the magnet  20 , and a stress-induced anisotropic magnetic field HA is applied due to the stress distribution. Thus, displacement of the magnetic bubble is generated and then the magnetic flux emitted from the magnetic bubble is detected by the plurality of the magnetic sensors  30   1 ,  30   2 ,  30   3 ,  30   11 ,  30   12 , . . . ,  30   1n  . . . ,  30   m1 ,  30   m2 , . . . ,  30   mn , and thereby the stress distribution can be detected. 
     Moreover, in the configuration shown in  FIG. 14 , physical damage to the plurality of the magnetic sensors  30   1 ,  30   2 ,  30   3 ,  30   11 ,  30   12 , . . . ,  30   1n  . . . ,  30   m1 ,  30   m2 , . . . ,  30   mn  is avoidable by disposing the plurality of the magnetic sensors  30   1 ,  30   2 ,  30   3 ,  30   11 ,  30   12 , . . . ,  30   1n  . . . ,  30   m1 ,  30   m2 , . . . ,  30   mn  so as to be opposed to the stress applied portion  40 P via the magnetic material  10 . 
     In the stress sensor  60  according to the modified example 8 of the embodiment, a stress in arbitrary positions can be detected by disposing the plurality of the magnetic sensors. 
     In the stress sensor  60  according to the modified example 8 of the embodiment, the magnetic sensors  30   1 ,  30   2 ,  30   3 ,  30   11 ,  30   12 , . . . ,  30   1n  . . . ,  30   m1 ,  30   m2 , . . . ,  30   mn  can be formed of a Hall element. Such a Hall element may be disposed so as to be contacted on the magnetic material  10 . 
     Although the magnetic flux emitted from the magnetic domain is decreased in accordance with distance, it can reduce attenuation of the magnetic flux to the minimum extent by disposing such a Hall element so as to be contacted on the magnetic material  10 , and thereby the magnetic flux can be efficiently detected. Accordingly, the magnetic sensor can be integrated with the stress sensor, and therefore it is preferred in the light of applicability of devices. 
     Moreover, the materials of the Hall element may be formed with bismuth (Bi). Bi has the maximum Hall coefficient in typical metals and can be fabricated by using vacuum evaporation etc., and thereby highly sensitive Hall elements can be fabricated not depending on underlying materials. 
     (Driving of Magnetic Domain Due to Local Stress) 
     (Selection of Magnetic Materials) 
     50-μm thick Bi-substituted garnet which is film-formed on an approximately 350-μm-thick (100) plane (CaGd) 3  (MgGaZr) 5 O 12  substrate by using liquid phase epitaxy was used for the magnetic material  10 . A saturation magnetization of the used magnetic material  10  is 343 G at a room temperature. The magnetic material  10  was subjected to an anneal process at 1000-1200 degrees C. for six hours in atmosphere. 
     If garnet is fabricated by using a liquid phase epitaxy, growth-induced magnetic anisotropy which is a phenomenon peculiar to the fabricating method appears. It has been known that the magnetic anisotropy will occur since ordering of a rare earth element spontaneously occurs during crystal growth by the growth-induced magnetic anisotropy, and thereby a vertical magnetization film can be obtained. Moreover, it has been known that such a growth-induced magnetic anisotropy can be reduced by an anneal process. Accordingly, the magnetic anisotropy of the magnetic material can be controlled by annealing temperature, and thereby a relationship between magnetic anisotropy and a stress response of the magnetic domain can be examined. 
       FIG. 15A  shows a relationship (magnetizing curve) between the external magnetic field Hex of the magnetic material  10  applied to the stress sensor according to the embodiment, and the magnetization M [an example without an anneal process];  FIG. 15B  shows an example of being annealed at 1150 degrees C.; and  FIG. 15C  shows an example of being annealed at 1200 degrees C. 
       FIG. 16  shows annealing temperature dependency between the saturation magnetic field Hs and a saturation magnetic field ratio (the quotient of the saturation magnetic field H s , ⊥ in an out-of-plane direction divided by the saturation magnetic field H s , ∥ in an in-plane direction), in the magnetic material  10  applied to the stress sensor according to the embodiment. As shown in  FIGS. 15A, 15B, and 16 , it is proved that the saturation magnetic field H s , ∥ in the in-plane direction with respect to the saturation magnetic field H s , ⊥ in the out-of-plane direction, is increased as the annealing temperature becomes increased. 
       FIG. 17A  shows the magnetic field dependency observed from a magnetooptical microscope image to be corresponded with the magnetizing curve (relationship between the external magnetic field Hex and the magnetization M), in the magnetic material  10  applied to the stress sensor according to the embodiment [an example before an anneal process]; and  FIG. 17B  shows an example of being annealed at 1200 degrees C. As shown in  FIGS. 17A and 17B , it is proved that stability regions of the magnetic bubbles BUB are expanded as the magnetizing curve is changed due to the anneal process. 
     (Measuring System of Magnetic Domain Motion Evaluation Due to Local Stress) 
       FIG. 18  shows a schematic configuration of a measuring system made by applying the Hall element  1  according to the embodiment, and combining an electromagnet  102  and a magnetooptical microscope capable of simultaneous measuring of Hall probe and imaging of magnetic domain motion. 
     In order to examine a magnetic domain motion phenomenon when applying the local stress, the local stress control system and the magnetooptical microscope measuring system as shown in  FIG. 18  were constructed. The measuring system is composed of a halogen tungsten lamp light source (hν), a permanent magnet (not shown), a polarizer  110 , a long-focus objective lens (CFI LU Plan EPI ELWD  x 50, Nikon Instruments Inc.) (not shown), am analyzer  106 , a charge coupled device (CCD) camera (C10600 ORCA-R 2 , Hamamatsu Photonics K. K.)  108 , and a local stress control system. The local stress control system includes: a tungsten needle  40 ; a micro-force sensor  42  connected to the tungsten needle  40 ; and a piezo lift stage  44  on which the tungsten needle  40  and the micro-force sensor  42  are mounted. 
     Linear polarization was entered into a sample (stress sensor  60 ) with Faraday configuration, and then CCD camera  108  detected the transmitted light from the sample through the analyzer  106 . A magnetic field strength with the permanent magnet in the stage position of the same measuring system is calibrated by a commercially available GaAs Hall element. A contact load of the tungsten needle  40  (tip curvature radius is 5 μm/ESSTech Inc.) to the sample is controlled by using the micro-force sensor  42  and the piezo lift stage (load resolution  20  is μN/Nano Control Co., Ltd.), and at the same time, magnetooptical microscope images of the sample can be observed. 
     In the present experiment, the tungsten needle  40  was disposed so as to be inclined at a 45 degrees angle made  45  in a sample normal direction so that the image may not be covered by the tungsten needle  40 . Although results of applying stresses using the tungsten needle  40  will now be shown hereafter, the aforementioned phenomenon was not caused by a magnetic interaction due to a magnetization of the needle, etc. since tungsten is a non-magnetic metal. Since the similar phenomenon occurred also when the stress is applied using a wooden toothpick, it was not caused by an electrostatic interaction due to electrification etc. Accordingly, the aforementioned phenomenon is a phenomenon which is purely caused by the stress. 
     (Magnetic Bubble Domain Generated Due to Local Stress) 
       FIG. 19A  shows a schematic cross-sectional structure (the magnetooptical microscope image corresponds to  FIG. 3A ) at the time when an annealing sample at an annealing temperature of 1200 degrees C. is applied to the saturation magnetic field (Hex=H s =560 (Oe): the magnetooptical microscope image corresponding to  FIG. 3  directing upward perpendicularly to the drawing sheet plane), in the magnetic material  10  applied to the stress sensor according to the embodiment. Moreover,  FIG. 19B  shows a schematic cross-sectional structure (magnetooptical microscope image corresponds to  FIG. 3B ) of the magnetooptical microscope image of the magnetic material  10  in which the stress-induced anisotropic magnetic field H A  is generated by applying the local stress to the magnetic material  10  with the tungsten needle  40 . Moreover,  FIG. 19C  shows a schematic cross-sectional structure (magnetooptical microscope image corresponds to  FIG. 3C ) of the magnetic material  10  in a (nonvolatile) state where the magnetizing direction which is reversed due to the stress-induced anisotropic magnetic field H A  is stored after the tungsten needle  40  is released. As shown in  FIGS. 19A to 19C , it is proved that it was in a single magnetic domain state before the tungsten needle  40  is contacted thereto, but the magnetic bubble domain is generated by applying the local stress. The aforementioned phenomenon can be explained as follows: 
     The local stress is generated by pushing the magnetic material  10  with the tungsten needle  40 . 
     A compressive stress is applied in-plane direction of the magnetic material  10  of the stress sensor  60 . With regard to a value of the quantitive stress, the stress and the direction can be calculabled with Hertzian contact theory or general Computer Aided Engineering (CAE) analysis. 
     The stress-induced anisotropic magnetic field H A  is generated in a perpendicular-to-plane direction of the magnetic material  10  in the stress sensor  60  (the magnetooptical microscope image corresponding to  FIG. 3  directing downward perpendicularly to the drawing sheet plane). 
     In this case, the stress-induced anisotropic magnetic field HA is generally expressed with the following equation (1): 
         H   A ∝−σλ  (1)
 
     where σ denotes an in-plane stress (positive: tensile stress, negative: compressive stress), and λ denotes magnetostrictive constant. 
     More specifically, the stress-induced anisotropic magnetic field HA is expressed with the following equation (2): 
         H   A =[2 K   1 −2σ(λ 100 +λ 111 )]/2 M   (2)
 
     where K 1  denotes cubic crystal anisotropy constant, (λ 100 +λ 111 ) denotes magnetostrictive constant, and M denotes saturation magnetization. In the equation (2), the stress-induced anisotropic magnetic field H A  is negative since σ and (λ 100 +λ 111 ) are negative. It was confirmed with the magnetostriction measurement that (λ 100 +λ 111 ) was negative. Accordingly, the magnetic bubble domain is generated due to the negative stress-induced anisotropic magnetic field H A . 
     Moreover, the above-mentioned phenomenon has a nonvolatile in that the magnetic bubble domain is generated at the time when the local stress is applied thereto, and the magnetic bubble domain is kept even if the tungsten needle  40  is released. Furthermore, there can also be realized a volatility in that the magnetic bubble domain can be generated only at the time when the local stress is applied thereto if the external magnetic field Hex is increased, and it will be returned to the saturation state if the tungsten needle  40  is released. 
     (Cutting of Striped Magnetic Domain Due to Local Stress) 
     In experimental examples of the stress sensor according to the embodiment,  FIG. 20A  shows a magnetooptical microscope image of the magnetic material  10  in a state where the external magnetic field Hex is not applied thereto (Hex=0 (Oe)) of the annealing sample at annealing temperature of 1200 degrees C. (before the tungsten needle is contacted). Moreover,  FIG. 20B  shows a magnetooptical microscope image in a state where the local stress (7.79 mN) is applied to the magnetic material  10  with the tungsten needle  40 , and  FIG. 20C  shows a difference image between  FIG. 20A  and  FIG. 20B . In  FIG. 20C , reference numeral B shows a portion of changing from the white ground (the magnetizing direction of the magnetic domain is directing upward perpendicularly to the drawing sheet plane) to the black ground (the magnetizing direction of the magnetic domain is directing downward perpendicularly to the drawing sheet plane). On the other hand, in  FIG. 20C , reference numeral C shows a portion of changing from the black ground (the magnetizing direction of the magnetic domain is directing downward perpendicularly to the drawing sheet plane) to the while ground (the magnetizing direction of the magnetic domain is directing upward perpendicularly to the drawing sheet plane). 
     As shown in  FIGS. 20A to 20C , it is proved that the striped magnetic domain is chopped by applying the local stress if the external magnetic field is not applied thereto. The aforementioned phenomenon can be explained as follows: 
     The local stress is generated by pushing the magnetic material  10  with the tungsten needle  40 . 
     The compressive stress is applied in an in-plane direction of the magnetic material  10 . 
     The stress-induced anisotropic magnetic field H A  is generated in a perpendicular-to-plane direction of the magnetic material  10  (the image is directing downward perpendicularly to the drawing sheet plane). 
     The striped magnetic domain of which the magnetizing direction is directing downward perpendicularly to the drawing sheet plane moves directly under the tungsten needle  40  at which the stress-induced anisotropic magnetic field H A  is generated. 
     The striped magnetic domains directing downward perpendicularly to the drawing sheet plane close to each other, and then the striped magnetic domain for minimizing the sum total of magnetostatic energy and domain wall energy is chopped. 
     (Displacement of Magnetic Bubble Domain Due to Local Stress) 
     On the other hand, in the experimental examples of the stress sensor according to the embodiment,  FIG. 21A  shows a magnetooptical microscope image of the magnetic material  10  in which a magnetic bubble domain is generated by applying a magnetic field for generating magnetic bubble domain (Hex-280 (Oe)) as the external magnetic field Hex of the annealing sample at annealing temperature of 1200 degrees C. thereto (before the tungsten needle is contacted (corresponding to  FIG. 5A )). Moreover,  FIG. 21B  shows a magnetooptical microscope image in a state where the local stress (1.15 mN) (corresponding to  FIG. 5B ) is applied to the magnetic material  10  with the tungsten needle  40 , and  FIG. 21C  shows a difference image between  FIG. 21A  and  FIG. 21B  (corresponding to  FIG. 5C ). As explained in  FIG. 5C , In  FIG. 21C , reference numerals R, B denote displacement of the magnetic bubble BUB. Accordingly, displacement of the magnetic bubbles BUB: R 1 →B 1 , R 2 →B 2 , R 3 →B 3 , R 4 →B 4 , R 5 →B 5 , R 6 →B 6 , R 7 →B 7 , and R 8 →B 8  are observed by applying the local stress (1.15 mN) to the magnetic material  10 . By applying the magnetic field for generating magnetic bubble to the magnetic material  10 , and applying the local stress thereto, the displacement of the magnetic bubble due to the stress distribution is generated, and thereby the stress distribution can also be detected by the plurality of the magnetic sensors  30 . 
     As shown in  FIG. 21A to 210 , it is proved that the magnetic bubble domain is displaced by applying the local stress to the magnetic material  10 . The aforementioned phenomenon can be explained as follows: 
     The local stress is generated by pushing the magnetic material  10  with the tungsten needle  40 . 
     The compressive stress is applied in in-plane direction of the magnetic material  10 . 
     The stress-induced anisotropic magnetic field H A  is generated in a perpendicular-to-plane direction of the magnetic material  10  (the image is directing downward perpendicularly to the drawing sheet plane). 
     The magnetic bubble domain moves directly under the tungsten needle  40  at which the stress-induced anisotropic magnetic field H A  is generated. 
     There are generated the in-plane distribution of the stress-induced anisotropic magnetic field H A  due to the stress distribution and the reconstruction of the magnetic bubble domain for minimizing the sum total of the magnetostatic energy and the domain wall energy, and thereby the magnetic bubble domain is displaced in a multibody state. 
     (External Magnetic Field and Local Stress Dependency of Magnetic Domain Motion Due to Local Stress) 
     In the magnetic material applied to the stress sensor according to the embodiment,  FIG. 22A  shows the magnetic field dependency of the magnetooptical microscope image to be corresponded with the magnetizing curve (relationship between the external magnetic field Hex and the magnetization M) [an example of being annealed at 1200 degrees C.] (corresponding to  FIG. 17B ).  FIG. 22B  is a diagram showing a relationship between the external magnetic field Hex and threshold force, in a result of examining a relationship between a magnetic domain motion and a threshold load, while changing magnetic domain structure by applying an external magnetic field Hex in perpendicular-to-plane direction thereto. In  FIG. 22B , “Move” shows threshold force f by which the stripe shaped magnetic domain or magnetic bubble domain directly under the tungsten needle  40  starts to move in a state where the external magnetic field Hex is applied. In  FIG. 22B , “Chop” shows threshold force f by which the stripe shaped magnetic domain directly under the tungsten needle  40  is chopped in the state where the external magnetic field Hex is applied. 
     As shown in  FIGS. 22A and 22B , it is proved that the phenomena, e.g. the motion and the chop of the striped magnetic domain, and the motion and the generation of the magnetic bubble domain, can be freely controlled with the external magnetic field and the local stress. Detailed experimental results are shown in  FIGS. 23 to 30 . In order to make aspects of the magnetic domain motion easily to understand,  FIGS. 31 to 38  show superimposed images before and after the displacement of the magnetic domain. Furthermore,  FIGS. 39 to 46  show difference images before and after the displacement of the magnetic domain. 
     As shown in  FIGS. 23 to 46 , the motion and the chop of the striped magnetic domain, and the motion and the generation of the magnetic bubble domain can be freely controlled with the external magnetic field Hex and the local stress. 
     (External Magnetic Field and Annealing Temperature (Magnetic Anisotropy) Dependency of Magnetic Domain Motion Threshold Load Due to Local Stress) 
       FIG. 47A  shows annealing temperature dependency (diagram corresponding to  FIG. 16 ) of between the saturation magnetic field Hs and a saturation magnetic field ratio H s , ⊥/H s , ∥, in the magnetic material applied to the stress sensor according to the embodiment.  FIG. 47B  shows annealing temperature dependency between the external magnetic field Hex (Oe) and the threshold force f (mN), showing an aspect that a threshold load of the magnetic domain motion is reduced by increasing the annealing temperature (reduction of magnetic anisotropy). 
     Regarding the results of the magnetic domain motion, only the magnetic materials  10  subjected to the anneal process at 1200 degrees C. has been shown until now.  FIGS. 47A and 47B  show the results of examining the threshold load of the magnetic domain motion with respect to the magnetic material  10  from which the annealing temperature, i.e., the magnetic anisotropy was changed by reducing the growth-induced magnetic anisotropy. As proved from  FIGS. 47A and 47B , the threshold load of the magnetic domain motion is reduced by increasing the annealing temperature, i.e., by reducing the magnetic anisotropy. 
     The above-mentioned results prove that the magnetic domain response with respect to the local stress can be controlled by controlling the magnetic anisotropy and the external magnetic field Hex of the magnetic material  10 . 
     (Local Magnetic Field Generating Apparatus) 
     A local magnetic field generating apparatus can be fabricated by applying the driving phenomenon of stress-induced magnetic domain. A simple structure of only combining the magnetic material  10  and the magnet  20  may be sufficient. 
     —Selection of Magnetic Substance Material— 
     As the magnetic materials  10 , if the materials capable of generating the magnetic bubble, a kind of the materials do not matter. For example, the magnetic materials  10  include: garnet RFe 5 O 12 , orthoferrite RFeO 3 , hexagonal crystal ferrite AFe 12 O 19  (R is a rare earth element and A is Ba, Sr, Pb, etc.). etc. known as magnetic bubble materials for many years; perovskite manganese oxide RRMnO 3  known as strongly-correlated electron materials (R is rare earth element or alkaline earth metal element); and helimagnet known as skyrmion materials (MnSi, MnGe, Mn 1-x Fe x Ge, FeGe, Fe 1-x Co x Si, Cu 2 O, SeO 3 ). The magnetic domain width, i.e., the spatial resolution of the local magnetic field, can be changed from several nm to several 100 μm by selecting the magnetic substance materials. 
     —Selection of Magnet— 
     Since the magnet  20  is used for applying the bubble generating magnetic field in the out-of-plane direction, a kind of the materials do not matter if the materials capable of realizing the purpose. Permanent magnets, electromagnets, or multi-ferroic materials which can control the magnetic field direction with voltage and current may be used. It is sufficient also as laminated structure using ferromagnetic material thin films. The magnets  20  are disposed so that the homogeneous magnetic field can be applied to the stress applied portion  40 P. 
       FIG. 48B  is a diagram explaining disposition of the magnet  20  in the local magnetic field generating apparatus, showing a configuration example in that the magnet  20  is disposed on the supporting base  70  so as to surround the magnetic material  10 .  FIG. 48B  shows a configuration example of disposing the magnet  20  on the magnetic material  10 . 
     The size of the external magnetic field Hex is adjusted so as to be the same degree of that of the saturation magnetic field Hs, on the magnetic material  10 . Moreover, the point that the function as the local magnetic field generating apparatus can be changed in accordance with the size of the applied external magnetic field Hex is the same as that of the stress sensor according to the embodiment (refer to  FIGS. 1 to 3 ). If the applied external magnetic field is set so as to be larger than the saturation magnetic field, the magnetizing direction is not stored after applying the stress. That is, on and off of the local magnetic field can be controlled by turning on and off of the stress. Accordingly, the volatile function can be realized. On the other hand, if the applied external magnetic field Hex is set so as to be the same degree of that of the saturation magnetic field Hs, the magnetizing direction is stored after applying the stress, i.e., the local magnetic field can be turned on by turning on of the stress. Accordingly, the nonvolatile function can be realized. 
     (Local Stress Sensor) 
     The local stress sensor can be fabricated by applying the driving phenomenon of stress-induced magnetic domain thereto, as the following procedures. As mentioned above, the disposition place of the magnet  20  for applying the external magnetic field Hex does not matter. 
     —Film Formation of Insulating Film— 
     The insulating film was deposited on the magnetic material  10 . If the magnetic material  10  has conductivity, for example, the magnetic material  10  and the magnetic sensor  30  can be made adjacent to each other via the insulating film, although the insulating film is not necessary if the magnetic material is an insulator. 
     —Fabrication of Magnetic Sensor— 
     The Hall element can be used as the magnetic sensor  30 . Hereinafter, although the case where the Hall element is used will now be described, it is possible to compose similarly the stress sensor even if other magnetic sensors are used, and therefore the magnetic sensor  30  is not limited to such a Hall element. For example, Tunnel Magneto-Resistance effect (TMR) elements, Giant Magneto Resistive effect (GMR) elements, etc. may be applied thereto. 
     It is preferable to select materials in which there is no damage to the magnetic materials  10 , e.g. vacuum evaporation and sputtering, and film formation is convenient, and thereby satisfactory characteristics are obtained in polycrystal films or amorphous films, as the Hall element material applied to a magnetic sensor  30 . If such materials are applied thereto, the magnetic material  10  can be formed so as to be laminated on the magnetic sensor  30 . Accordingly, the magnetic flux from the magnetic domain can be efficiently detected, without the magnetic flux from the magnetic domain decaying, since the distance between the magnetic material  10  and the magnetic sensors  30  is increased. As materials which can be conveniently fabricated with vacuum evaporation, Bi which is a semimetal with a high degree of Hall coefficient is listed, for example. 
       FIG. 49  shows a relationship between a magnetic sensor output and a local stress (or stress-induced anisotropic magnetic field), in the stress sensor  60  according to the embodiment configured to using a Hall element as the magnetic sensor  30 . Moreover,  FIG. 50A  is a schematic diagram showing the magnetic sensor  30  corresponding to the point A shown in  FIG. 49 , for explaining an aspect that an area of the magnetic bubble which occupies directly under an effective region of the magnetic sensor gradually increases by increasing the stress. Moreover,  FIG. 50B  is a schematic diagram showing a magnetic bubble BB 1  corresponding to the point B shown in  FIG. 49 , FIG.  50 C is a schematic diagram showing a magnetic bubble BB 2  corresponding to the point C shown in  FIG. 49 , and  FIG. 50D  is a schematic diagram showing a magnetic bubble BB 3  corresponding to the point D shown in  FIG. 49 . 
     If it is concerned about a damage to the magnetic sensor  30  due to the stress, the magnetic sensor  30  may be formed on a surface opposite to a surface to which the stress is applied, for example. Hole crossbar and a pad electrode were formed on the magnetic material  10  with general photolithography method. In this case, the magnitude relationship between the hole crossbar and the magnetic domain width can add the following function. That is, when applying the local stress to the magnetic material  10 , the magnetic bubble will be generated if a certain constant threshold stress is applied, but if the stress is further increased, a phenomenon in which the diameter of the magnetic bubble becomes large will be used positively. 
     As shown in  FIGS. 49 and 50A-50D , if the magnetic bubble diameter is increased by increasing the stress, the area of the magnetic bubble occupied directly under the magnetic sensor effective region will be gradually increased. Changes of minuter stresses can be detected since the magnetic sensor output is increased corresponding thereto. It is also preferable to integrate a plurality of the magnetic sensors on the magnetic material in order to detect the local stress at arbitrary positions on the magnetic material front side surface. 
     (Stress Distribution Sensor) 
     The stress distribution sensor can be fabricated by applying the driving phenomenon of stress-induced magnetic domain. As shown in  FIGS. 20 and 21 , if the stress is given in a state of applying the magnetic field for generating magnetic bubble, there will be generated the in-plane distribution of the stress-induced anisotropic magnetic field H A  due to the stress distribution and the reconstruction of the magnetic bubble domain for minimizing the sum total of the magnetostatic energy and the domain wall energy, and thereby the magnetic bubble domain is displaced in a multibody state. The stress distribution can be measured by detecting the displacement of the bubbles by using a plurality of the magnetic sensor integrated on the magnetic material. 
     In addition, stresses between materials applying the stress and the materials receiving the stress (e.g., magnetic material, in this case) are changed with a physical property value of the materials (e.g., elastic coefficient, Poisson&#39;s ratio, and friction coefficient if friction is need to be taken into consideration). For example, it becomes possible to experimentally measure the stress for two bodies with higher accuracy by performing the following processes: That is, a relationship between the applied stress and the magnetic sensor output is checked as reference data by contacting a needle provided at an edge part of the micro-force sensor to the magnetic material, while the stress is controlled using the piezo lift stage. Furthermore, in consideration of the physical property values, stress calculation with the Hertzian contact theory or general CAE analysis is executed, and then a simulation of applying the stress is performed. 
     (Hall Element) 
       FIG. 51  shows a schematic planar pattern configuration of the Hall element  1  applicable to the magnetic sensor in the stress sensor according to the embodiment, and  FIG. 52  shows a schematic bird&#39;s-eye view configuration thereof. 
     Moreover,  FIG. 53  shows a surface optical micrograph of one element portion of the Hall element  1 , and  FIG. 54  shows a schematic cross-sectional structure taken in the line of  FIG. 53 . 
     As shown in  FIGS. 51 to 54 , the Hall element  1  includes: a crossbar-shaped electrode layer  140  disposed on a magnetic material  100 ; and pad electrodes P 1 -P 4 ,  160 ,  180  connected to the crossbar portion of the electrode layer  140 . 
     In the embodiment, the electrode layer  140  having crossbar shape is formed of an approximately 100-nm-thick Bi electrode layer. Moreover, if the underlying metal layer is disposed as an underlying layer of the bismuth electrode layer  140 , an effect of Bi lift off can be improved in a Lift-off process of the bismuth electrode layer  140 . An approximately 3-nm-thick Cr layer can be applied as the underlying metal layer, for example. 
       FIG. 55  shows a SEM photograph of the surface at the center portion of hole crossbar in the Hall element  1  and an explanatory diagram of the center portion of hole crossbar. The area of the crossbar portion can be formed in various sizes in the Hall element  1 . The crossbar portion of the crossbar-shaped electrode layer  140  may have sizes (W 1 =W 2 ) of several 10 nm to several 100 μm. Alternatively, the sizes may be equal to or less than 100 nm×100 nm. More specifically, as shown in  FIG. 55 , the crossbar portion of the crossbar-shaped electrode layer  140  may have the sizes (W 1 ×W 2 ) of equal to or less than 100 nm×100 nm, or preferably may be 50 nm×50 nm, for example. 
     Moreover, as shown in  FIGS. 51 to 54 , the Hall element  1  may include an insulating layer  120  disposed between the magnetic material  100  and the electrode layer  140 . Since the Hall element  1  includes the insulating layer  120 , the electrode layer  140  and the pad electrodes P 1 -P 4 ,  160 ,  180  can be formed so as to be integrated with the magnetic material  100 . Thus, the Hall element  1  integrated with the magnetic material  100  composes the magnetic sensor. Accordingly, such a detection device formed so as to be integrated with the magnetic material  100  can be called the magnetic sensor applicable to the stress sensor according to the embodiment in this way. 
     In the magnetic sensor to which the Hall element  1  is applied, the magnetic material  100  may be formed of a B 1 -substituted garnet, for example. An approximately 50-μm-thick Bi-substituted garnet which is film-formed on an approximately 350-μm-thick (111) plane (GaGd) 3 (MgGaZr) 5 O 12  substrate by using liquid phase epitaxy may be used for the magnetic material  100 . 
     Moreover, the insulating layer  120  may be formed of an approximately 30-nm-thick Al 2 O 3 , for example, in the magnetic sensor to which the Hall element  1  is applied. In the embodiment, the Al 2 O 3  can be formed by using the Atomic Layer Deposition (ALD) method, for example. 
     Moreover, the pad electrodes P 1 -P 4 ,  160 ,  180  may include an Au layer, in the magnetic sensor to which the Hall element  1  is applied. More specifically, the pad electrodes P 1 -P 4 ,  160 ,  180  may be formed of a structure formed by laminating an approximately 5-nm-thick Cr layer/an approximately 200-nm-thick Au layer/an approximately 5-nm-thick Cr layer. 
     Moreover, the magnetic sensor to which the Hall element  1  is applied may include a passivation film  200  configured to cover the front side surface of device, as shown in  FIG. 54 . In the embodiment, the passivation film  200  may be formed of an approximately 30-nm-thick Al 2 O 3 , for example. Similarly, the Al 2 O 3  can be formed by using the ALD method, for example. Degradation due to oxidization of the bismuth electrode layer  14  having crossbar-shaped underlying can be prevented by applying the ALD-Al 2 O 3  layer as the passivation film  200 . 
     Moreover, in the magnetic sensor to which the Hall element  1  is applied, as shown in  FIG. 54 , apertures  160 H,  180 H with respect to the pad electrodes  160 ,  180  may be formed in the passivation film  200  (refer to  FIG. 59D ), and bonding wires  220   1 ,  220   2  may be connected to the pad electrodes  160 ,  180  in the apertures  160 H,  180 H. Note that the bonding wires  220   1 ,  220   2  shown in  FIG. 54  are omitted in  FIG. 53 . 
     In the magnetic sensor to which the Hall element  1  is applied, current I O  is conducted in a P 2  direction from the pad electrode P 4  of pad electrodes P 1 -P 4  formed to be integrated with the magnetic material  100 , and then between the pad electrodes P 1  and P 4 , an output hall voltage V H  (μV) expressed in the following equation is generated, where B O  is a magnetic field (magnetic flux density) applied from the magnetic material  100  to the crossbar portion, and K H  (V/(A·T)) is product sensitivity: 
         V   H   =K   H   ×I   C   ×B   O   (3)
 
     where the product sensitivity K H  (V/(A·T)) is a constant determined in accordance with the materials and geometrical dimensions, for example, and is 4.4 (V/(A·T)). 
     The bismuth electrode layer  140  has the maximum Hall coefficient in typical metals and can be fabricated by using vacuum evaporation etc., and thereby highly sensitive Hall elements can be fabricated not depending on underlying materials, in the Hall element  1 . 
     In the magnetic sensor to which the Hall element  1  is applied, it becomes detecting a minute magnetic domain by making the size of the Hall element  1  smaller. There is no characteristic degradation under an effect of the surface depletion due to minuteness of the element such as a semiconductor Hall element since Bi composing the electrode layer  140  is a semimetal. 
     The insulating layer  120  is inserted between the Hall element  1  and the magnetic material  100 , and thereby the magnetic sensor to which the Hall element  1  is applied can be applied thereto not dependent on the electrical conductivity of the magnetic material  100 . 
       FIG. 56  shows a relationship between an output hall voltage V H  (μV) and an output magnetic field BO, and the applied magnetic field B, in an explanatory diagram of a Hall probe operation droved by an applied magnetic field B, in the magnetic sensor to which the Hall element  1  is applied. In the embodiment, the applied magnetic field B is a magnetic field applied from external, and is supplied to the magnetic sensor to which the Hall element  1  is applied from an electromagnet by a measuring system made by combining an electromagnet and magnetooptical microscope by which the Hall probe of the magnetic domain motion and imaging can be simultaneously measured. 
     Moreover,  FIG. 57A  shows an example of a bubble domain DM (−) of the garnet magnetic material existing directly under the center portion of hole crossbar, in the magnetic sensor to which the Hall element  1  is applied, and  FIG. 57B  shows an example of a bubble domain DM (+) of the garnet magnetic material existing directly under the center portion of hole crossbar, in the magnetic sensor to which the Hall element  1  is applied. The example of the bubble domain DM (−) of the garnet magnetic material existing directly under the center portion of hole crossbar corresponds to an example of the output magnetic field B O  being generated in the direction from the upper surface of the drawing sheet to the back side surface, and corresponds to the thick line arrow in  FIG. 56  (the output magnetic field B O  moves from positive direction to the negative direction). On the other hand, the example of the bubble domain DM (+) of the garnet magnetic material existing directly under the center portion of hole crossbar corresponds to an example of the output magnetic field B O  being generated in the direction from the back surface of the drawing sheet to the upper side surface, and corresponds to the thin line arrow in  FIG. 56  (the output magnetic field B O  moves from negative direction to the positive direction). 
     As shown in  FIGS. 56, 57A, and 57B , a switching operation of the output hall voltage V H  can be confirmed with the magnetic domain motion of the garnet magnetic material  100 , in the magnetic sensor to which the Hall element  1  is applied. That is, the switching operation of the output hall voltage V H  due to the magnetic domain crossing directly under the Hall element  1  can be confirmed. 
     A quantitative evaluation of a magnetic domain motion and evaluation of an external applied magnetic field response according to the electric detection can be realized by the measuring system (refer to  FIG. 18 ) made by combining the electromagnet and the magnetooptical microscope by which the Hall probe of the magnetic domain motion and imaging can be simultaneously measured. 
     As shown in  FIGS. 56, 57A, and 57B , the magnetic domain motion of the garnet magnetic material  100  can be detected by driving the external magnetic field, in the magnetic sensor to which the Hall element  1  is applied. 
       FIG. 58A  shows an example of sizes of each portion of the magnetic material  100  (domain width d, and thickness t of the magnetic recording medium), in the magnetic sensor to which the Hall element  1  is applied.  FIG. 58B  shows a relationship between a vertical magnetic flux density B Z  (mT) and the height Z of the magnetic field with respect to the magnetic material  100 , using the domain width d as a parameter. In  FIG. 58B , the thickness t of the magnetic recording medium is set to 100 nm which is a constant value. 
     The vertical magnetic field B Z  is expressed as a function of the height Z with the following equation (W. Straus, JAP 42, 1251 (1971)): 
         B   Z   =M   Z [(α+1)/{(α+1) 2 +β 2 } 1/2 −(α−1)/{(α−1) 2 +β 2 } 1/2 ]  (4)
 
     where M Z  is saturation magnetization, α=2Z/t, and β=d/t. 
     In the magnetic sensor to which the Hall element  1  is applied, the magnetic fields B Z  will be decreased, as the height Z is increased, the domain width d is decreased, the thickness t of the magnetic material is decreased. 
     That is, the magnetic fields B Z  emitted from the magnetic domain will be decreased in accordance with the height Z being increased, and such a tendency generally becomes remarkable in accordance with reduction of the domain width d and the magnetic recording medium thickness t. 
     It is preferable to closely dispose Hall element  1  to the magnetic domain (domain), in the magnetic sensor to which the Hall element  1  according to the embodiment is applied. 
     (Measuring System) 
     A schematic configuration of a measuring system made by applying the Hall element  1  according to the embodiment, and combining an electromagnet  102  and a magnetooptical microscope capable of simultaneous measuring of Hall probe and imaging of magnetic domain motion is expressed as similarly shown in  FIG. 18 . The measured results of imaging of the magnetic domain motion are photographs shown in  FIGS. 57A and 57B , for example. 
     (Fabrication Method for Magnetic Sensor) 
       FIG. 59A  is a schematic cross-sectional structure showing forming an insulating layer  120  after forming an alignment electrode layer  170  on the magnetic material  100 , in an explanatory diagram of a fabrication method for the magnetic sensor to which the Hall element  1  is applied. 
       FIG. 59B  is a schematic cross-sectional structure showing pattern-forming a bismuth (Bi) electrode layer  140  on the insulating layer  120 . 
       FIG. 59C  shows a schematic cross-sectional structure which shows forming a passivation film  200  on the entire surface after pattern-forming a pad electrode  160 ,  180  in contact with the bismuth electrode layer  140 . 
       FIG. 59D  is a schematic cross-sectional structure which shows forming contact holes  160 H,  180 H into the pad electrode  160 ,  180 . 
     The fabrication method of the magnetic sensor to which the Hall element  1  is applied includes: forming an insulating layer  120  on the magnetic material  100 ; pattern-forming a bismuth electrode layer  140  on the insulating layer  120 ; pattern-forming pad electrodes  160 ,  180  on the bismuth electrode layer  140 ; forming a passivation film  200  on the pad electrodes  160 ,  180 ; forming apertures  160 H,  180 H with respect to the pad electrodes  160 ,  180  in the passivation film  200 ; and respectively connecting bonding wires  220   1 ,  220   2  to the apertures  160 H,  180 H. 
     Moreover. the step of pattern-forming the bismuth electrode layer  140  on the insulating layer  120  may include: forming a resist layer on the magnetic material  100 ; forming a bismuth electrode layer  140  on the resist layer; and performing a Lift-off process of the resist layer. 
     Moreover, the step of forming the resist layer on the magnetic material  100  may include a plurarity of resist layers step, e.g., forming a positive resist layer (ZEP520) on PMGI, after forming PMGI on the magnetic material  100 . 
     Hereinafter, the fabrication method for the magnetic sensor to which the Hall element  1  is applied will now be explained in details. 
     (a) Firstly, as shown in  FIG. 59A , in accordance with a first lithography process, after pattern formation of the alignment electrode layer  170  on the magnetic material  100 , the insulating layer  120  is formed.
 
(a-1) More specifically, the alignment electrode layer  170  composed of a laminating layer of Cr (5 nm)/Au (200 nm)/Cr (5 nm) is pattern-formed on the magnetic material  100  by using the electron beam evaporation method and the Lift-off process.
 
(a-2) Next, the insulating layer  120  composed of Al 2 O 3  (layer thickness: approximately 30 nm, oxygen supply source: H 2 O, film formation temperature: approximately 100 degrees C.) is formed by using the ALD method.
 
(b) Next, as shown in  FIG. 59B , a hole crossbar is pattern-formed on the insulating layer  120  according to a second lithography process.
 
(b-1) More specifically, Cr (3 nm) layer is pattern-formed on the insulating layer  120  by using the electron beam evaporation method.
 
(b-2) Next, an approximately 100-nm-thick bismuth electrode layer  140  is pattern-formed by using the resistance heating vacuum evaporation method and the Lift-off process method.
 
(c) Next, as shown in  FIG. 59C , according to a third lithography process, the pad electrodes  160 ,  180  are pattern-formed on the insulating layer  120  so as to be contacted with the bismuth electrode layer  140 .
 
(c-1) More specifically, the pad electrodes  160 ,  180  composed of laminating layer of Cr (5 nm)/Au (200 nm)/Cr (5 nm) are pattern-formed on the insulating layer  120 , by using the electron beam evaporation method and the Lift-off process, so as to be contacted with the bismuth electrode layer  140 .
 
(c-2) Next, the passivation film  200  composed of Al 2 O 3  (layer thickness: approximately 30 nm, oxygen supply source: H 2 O, film formation temperature: approximately 100 degrees C.) is formed by using the ALD method.
 
(d) Next, as shown in  FIG. 59D , the contact holes are pattern-formed with respect to the pad electrodes  160   180  according to a fourth lithography process.
 
(d-1) More specifically, the passivation film  200  composed of Al 2 O 3  is etched with dilute phosphoric acid H 3 PO 4  (phosphoric acid:pure water=1:4, approximately 60 degrees C.).
 
(d-2) Furthermore, the Cr layer is etched by using the Reactive Ion Etching (RIE) method (Cl 2 /O 2 =2/2 sccm, pressure of 0.2 Pa, power of 100 W).
 
     As explained above, according to the embodiment, there can be provided the stress sensor which can detect the local stress with the convenience structure, and can obtain the high spatial resolution by using the stress response phenomenon of the single magnetic domain; and the fabrication method for such a stress sensor. 
     OTHER EMBODIMENTS 
     As explained above, the embodiment has been described, as a disclosure including associated description and drawings to be construed as illustrative, not restrictive. This disclosure makes clear a variety of alternative embodiment, working examples, and operational techniques for those skilled in the art. 
     Such being the case, the embodiment covers a variety of embodiments, whether described or not. 
     INDUSTRIAL APPLICABILITY 
     The stress sensor according to the embodiment can be applied to technical fields associated with detection of mechanical forces, and can be applied to strain sensors, pressure sensors, etc.