Abstract:
A soft magnetic film includes a ferromagnetic layer. The ferromagnetic layer is laid over a non-magnetic substructure including ferromagnetic atoms. The uniaxial magnetic anisotropy may be established in the ferromagnetic layer. Since a magnetic property is not required in the substructure under the ferromagnetic layer, the soft magnetic film of this type may be utilized for purposes of wider variations.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a soft magnetic film, and in particular to a soft magnetic film mainly utilized in a magnetic pole for a thin film magnetic head. 
   In this specification, the content of an element in alloy is determined based on the atomic percentage. 
   2. Description of the Prior Art 
   For example, an iron cobalt nitrogen (FeCoN) alloy layer is well known. The FeCoN alloy layer realizes a relatively higher saturation magnetic flux density such as 2.4 [T] approximately. In addition, if the FeCoN alloy layer is laid over the nickel iron (NiFe) ferromagnetic layer, a good magnetic anisotropy can be obtained in the FeCoN alloy layer. See IEEE Transactions on Magnetics, Vol. 36, No. 5, September 2000, pp2506–2508, for example. The FeCoN alloy layer on the NiFe ferromagnetic layer exhibits a soft higher saturation magnetization. 
   A still higher saturation magnetization is required for the upper and lower magnetic poles in a thin film magnetic or inductive write head utilized to write bit data in a hard disk drive (HDD), for example. A higher saturation magnetization leads to generation of a stronger magnetic field for recording at the write gap of the thin film magnetic head. A stronger magnetic field for recording largely contributes to a still increased recording density. A higher saturation magnetization is expected in a soft magnetic film. 
   For example, the aforementioned FeCoN alloy layer may be utilized as the upper magnetic pole of the thin film magnetic head. However, the aforementioned FeCoN alloy layer should be accompanied by a substratum of the NiFe ferromagnetic layer for establishment of a predetermined magnetic anisotropy. Accordingly, the NiFe ferromagnetic layer has to be interposed between the upper magnetic pole and the non-magnetic spacer or gap layer. Since the NiFe ferromagnetic layer only exhibits the saturation magnetization of 1.1 [T] approximately, the utilization of the FeCoN alloy layer fails to lead to establishment of a stronger magnetic field for recording. 
   SUMMARY OF THE INVENTION 
   It is accordingly an object of the present invention to provide a soft magnetic film greatly contributing to establishment of a stronger magnetic field for recording in a thin film magnetic head. 
   According to the present invention, there is provided a soft magnetic film comprising: a ferromagnetic layer laid over a non-magnetic substructure including ferromagnetic atoms. 
   When the ferromagnetic layer is formed to extend over the non-magnetic substructure including ferromagnetic atoms, the uniaxial magnetic anisotropy is established in the ferromagnetic layer. The soft magnetic property can be established in the ferromagnetic layer. In addition, a magnetic property is not required in the substructure under the ferromagnetic layer. The soft magnetic film of this type may be utilized for purposes of wider variations. 
   The ferromagnetic atoms in the non-magnetic substructure may belong to at least an element selected from a group consisting of Fe, Ni and Co. The non-magnetic substructure may be made of NiFe alloy. The non-magnetic substructure may further contain at least an atom belonging to an element selected from a group consisting of Al, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo W, Rh, Ru, Pd and Pt. For example, if the Cr atoms are contained in the NiFe alloy at content equal to or larger than 25 at %, the complete non-magnetic property can be obtained in the NiFe alloy. 
   The ferromagnetic layer may be made of alloy containing an atom belonging to at least an element selected from a group consisting of Fe and Co. The alloy may be iron cobalt (FeCo) alloy. The alloy of this type is allowed to exhibit a higher saturation magnetic flux density. The iron cobalt alloy may contain at least an atom belonging to an element selected from a group consisting of O, N and C. In addition, the iron cobalt alloy may further contain at least an atom belonging to an element selected from a group consisting of Al, B, Ga, Si, Ge, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Ni, Mo, W, Rh, Ru, Pd and Pt. 
   The soft magnetic film of the aforementioned type may be utilized as a magnetic pole of a thin film magnetic head. The thin film magnetic head is in general used to write bit data into a magnetic recording medium in a magnetic recording medium drive such as a hard disk drive (HDD). The thin film magnetic head may include: a lower magnetic pole; a non-magnetic layer laid over the lower magnetic pole; a non-magnetic substratum laid over the non-magnetic layer and containing ferromagnetic atoms; and an upper magnetic pole laid over the non-magnetic substratum and containing ferromagnetic atoms. The soft magnetic layer of the aforementioned type may be utilized as the upper magnetic pole laid over the non-magnetic substratum. The thin film magnetic head may be mounted on a head slider incorporated within the HDD, for example. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiment in conjunction with the accompanying drawings, wherein: 
       FIG. 1  is a plan view schematically illustrating the structure of a hard disk drive (HDD); 
       FIG. 2  is an enlarged perspective view of a flying head slider according to a specific example; 
       FIG. 3  is an enlarged plan view schematically illustrating the structure of a thin film magnetic or inductive write head according to the present invention; 
       FIG. 4  is a sectional view taken along the line  4 — 4  in  FIG. 3 ; 
       FIG. 5  is a partial sectional view of a wafer for schematically illustrating a method of making a lower magnetic pole and a swirly coil pattern; 
       FIG. 6  is a partial sectional view of the wafer for schematically illustrating a photoresist film corresponding to the shape of an upper magnetic pole; 
       FIG. 7  is a schematic view illustrating a method of making a ferromagnetic layer on a non-magnetic substratum based on a so-called revolving deposition; 
       FIG. 8  is an enlarged plan view of the wafer for schematically illustrating the image of the magnetic anisotropy established based on the revolving deposition; 
       FIG. 9  is a view, corresponding to the sectional view taken along the line  9 — 9  in  FIG. 6 , for schematically illustrating a trimming process for the upper magnetic pole; 
       FIG. 10  is a graph illustrating the relationship between the content of Cr in NiFe alloy and the saturation magnetic flux density; 
       FIG. 11  is a graph illustrating the BH hysteresis of a ferromagnetic layer of FeCoAlO alloy or soft magnetic layer according to the present invention; 
       FIG. 12  is a graph illustrating the BH hysteresis of a ferromagnetic layer of FeCoAlO alloy according to a first comparative example; 
       FIG. 13  is a graph illustrating the BH hysteresis of a ferromagnetic layer of FeCoAlO alloy according to a second comparative example; 
       FIG. 14  is a graph illustrating the relationship between the ratio of the residual magnetic flux density to the saturation magnetic flux density and the angle of the BH measurement in the deposited ferromagnetic layer of the FeCoAlO alloy; 
       FIG. 15  is a graph illustrating the relationship between the ratio of the residual magnetic flux density to the saturation magnetic flux density and the angle of the BH measurement in the ferromagnetic layer of the FeCoAlO alloy after application of a linear magnetic field under a high temperature condition; 
       FIG. 16  is a graph illustrating the BH hysteresis of a ferromagnetic layer of FeCo alloy or soft magnetic layer according to the present invention; and 
       FIG. 17  is a graph illustrating the BH hysteresis of a ferromagnetic layer of FeCo alloy according to a comparative example. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  schematically illustrates the inner structure of a hard disk drive (HDD)  11  as an example of a recording medium drive or storage device. The HDD  11  includes a box-shaped primary enclosure  12  defining an inner space of a flat parallelepiped, for example. At least one magnetic recording disk  13  is accommodated in the inner space within the primary enclosure  12 . The magnetic recording disk  13  is mounted on the driving shaft of a spindle motor  14 . The spindle motor  14  is allowed to drive the magnetic recording disk  13  for rotation at a higher revolution speed such as 7,200 rpm or 10,000 rpm, for example. A cover, not shown, is coupled to the primary enclosure  12  so as to define the closed inner space between the primary enclosure  12  and itself. 
   A carriage  16  is also accommodated in the inner space of the primary enclosure  12 . The carriage  16  is designed to swing about a vertical support shaft  15 . The carriage  16  includes a rigid swinging arm  17  extending in the horizontal direction from the vertical support shaft  15 , and an elastic head suspension  18  fixed to the tip end of the swinging arm  17 . The elastic head suspension  18  extends forward from the swinging arm  17 . As conventionally known, a flying head slider  19  is cantilevered at the head suspension  18  through a gimbal spring, not shown. The head suspension  18  serves to urge the flying head slider  19  toward the surface of the magnetic recording disk  13 . When the magnetic recording disk  13  rotates, the flying head slider  19  is allowed to receive airflow generated along the rotating magnetic recording disk  13 . The airflow serves to generate a lift on the flying head slider  19 . The flying head slider  19  is thus allowed to keep flying above the surface of the magnetic recording disk  13  during rotation of the magnetic recording disk  13  at a higher stability established by the balance between the lift and the urging force of the head suspension  18 . 
   When the carriage  16  is driven to swing about the support shaft  15  during the flight of the flying head slider  19 , the flying head slider  19  is allowed to cross the recording tracks defined on the magnetic recording disk  13  in the radial direction of the magnetic recording disk  13 . This radial movement serves to position the flying head slider  19  right above a target recording track on the magnetic recording disk  13 . In this case, an electromagnetic actuator  21  such as a voice coil motor (VCM) can be employed to realize the swinging movement of the carriage  16 , for example. As conventionally known, in the case where two or more magnetic recording disks  13  are incorporated within the inner space of the primary enclosure  12 , a pair of the elastic head suspensions  18  and the swinging arms  17  are disposed between the adjacent magnetic recording disks  13 . 
     FIG. 2  illustrates a specific example of the flying head slider  19 . The flying head slider  19  of this type includes a slider body  22  made of Al 2 O 3 —TiC in the form of a flat parallelepiped, and a head protection layer  24  coupled to the trailing or outflow end of the slider body  22 . The head protection layer  24  may be made of Al 2 O 3 . A read/write electromagnetic transducer  23  is embedded in the head protection layer  24 . A medium-opposed surface or bottom surface  25  is defined continuously over the slider body  22  and the head protection layer  24  so as to face the surface of the magnetic recording disk  13  at a distance. The bottom surface  25  is designed to receive airflow  26  generated along the surface of the rotating magnetic recording disk  13 . 
   A pair of rails  27  are formed to extend over the bottom surface  25  from the leading or inflow end toward the trailing or outflow end. The individual rail  27  is designed to define an air bearing surface  28  at its top surface. In particular, the airflow  26  generates the aforementioned lift at the respective air bearing surfaces  28 . The read/write electromagnetic transducer  23  embedded in the head protection layer  24  is designed to expose the front end at the air bearing surface  28  as described later in detail. A diamond-like-carbon (DLC) protection layer may additionally be formed to extend over the air bearing surface  28  to cover over the front end of the read/write electromagnetic transducer  23 . The flying head slider  19  may take any shape or form other than the above-described one. 
   As shown in  FIG. 3  in detail, the read/write electromagnetic transducer  23  includes a thin film magnetic or inductive write head  32  according to an embodiment of the present invention. The thin film magnetic head  32  is designed to utilize a magnetic field induced at a conductive swirly coil pattern  31  so as to record magnetic binary data in to the magnetic recording disk  13 . When a magnetic field is induced at the swirly coil pattern  31  in response to supply of an electric current, a magnetic flux is allowed to circulate through a magnetic core  33  penetrating through the swirly coil pattern  31  at its central position. The swirly coil pattern  31  may be made from a conductive metallic material such as Cu, for example. 
   Referring also to  FIG. 4 , the magnetic core  33  includes lower and upper magnetic poles  34 ,  35  extending forward from the central position of the swirly coil pattern  31  toward the bottom surface  25 . The front ends of the lower and upper magnetic poles  34 ,  35  get exposed at the air bearing surface  28 . The lower magnetic pole  34  includes a primary magnetic pole layer  34   a  and a front magnetic pole piece  34   b  standing on the upper surface of the primary magnetic pole layer  34   a  outside the swirly coil pattern  31 . The front magnetic pole piece  34   b  is disposed adjacent the air bearing surface  28 . The lower magnetic pole  34  further includes a rear magnetic pole piece  34   c  standing on the upper surface of the primary magnetic pole layer  34   a  at the central position of the swirly coil pattern  31 . The top surfaces of the front and rear magnetic pole pieces  34   b ,  34   c  are positioned within a flat surface  36 . The lower magnetic pole  34  may be made of NiFe, for example. 
   A non-magnetic layer  37  is laid over the lower magnetic pole  34  so as to extend on the flat surface  36 . The non-magnetic layer  37  is designed to extend rearward from the front end exposed at the air bearing surface  28 . A non-magnetic substratum or substructure  38  is laid over the non-magnetic layer  37 . The non-magnetic substratum  38  contains ferromagnetic atoms. The front end of the upper magnetic pole  35  is received on the upper surface of the non-magnetic substratum  38 . The non-magnetic substratum  38  is in this manner interposed between the lower and upper magnetic poles  34 ,  35  along with the non-magnetic layer  37 . A write gap is thus defined between the lower and upper magnetic poles  34 ,  35 . It should be noted that the non-magnetic substratum  38  may solely be interposed between the lower and upper magnetic poles  34 ,  35 . 
   The non-magnetic substratum  38  may be made of nickel iron (NiFe) alloy containing Cr at a content equal to or larger than 25 at %. Alternatively, the non-magnetic substratum  38  may be made of an alloy containing ferromagnetic atoms belonging to at least an element selected from a group consisting of Fe, Ni and Co. In the latter case, the alloy may further contain at least a non-magnetic atom belonging to an element selected from a group consisting of Al, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Rh, Ru, Pd and Pt. The non-magnetic atoms serves to establish the non-magnetic property of the alloy. 
   The upper magnetic pole  35  includes a ferromagnetic layer  35   a  laid over the non-magnetic substratum  38  and a primary magnetic pole layer  35   b  designed to extend forward from the central position of the swirly coil pattern  31 . At least the front end of the primary magnetic pole layer  35   b  is received on the ferromagnetic layer  35   a . The upper magnetic pole  35  is designed to oppose the ferromagnetic layer  35   a  to the lower magnetic pole  34 . The rear end of the upper magnetic pole  35  is connected to the rear magnetic pole piece  34   c  of the lower magnetic pole  34  at the central position of the swirly coil pattern  31 . 
   The ferromagnetic layer  35   a  may be made of iron cobalt (FeCo) alloy, for example. The FeCo alloy may further contain at least an atom belonging to an element selected from a group consisting of O, N and C. The FeCo alloy may still further contain at least an atom belonging to an element selected from a group consisting of Al, B, Ga, Si, Ge, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Ni, Mo, W, Rh, Ru, Pd and Pt. Alternatively, the ferromagnetic layer  35   a  may be made of an alloy containing ferromagnetic atoms belonging to at least an element selected from a group consisting of Fe and Co. The ferromagnetic layer  35   a  on the non-magnetic substratum  38  exhibits a soft magnetic property as well as a higher saturation magnetic flux density or saturation magnetization larger than 2.4[T] approximately as described later in detail. The primary magnetic pole layer  35   b  may be made of NiFe, for example. 
   As shown in  FIG. 4 , the read/write electromagnetic transducer  23  further includes a read head  42 . The read head  42  is designed to utilize a magnetoresistive element  41  so as to discriminate magnetic bit data on the magnetic recording disk  13 . As conventionally known, the magnetoresistive element  41  is interposed between upper and lower shield layers  43 ,  44 . A read gap is defined between the upper and lower shield layers  43 ,  44 . The upper and lower shield layers  43 ,  44  may be made of a magnetic material such as FeN, NiFe, or the like. The magnetoresistive element  41  maybe a giant magnetoresistive (GMR) element, a tunnel-junction magnetoresistive (TMR) element, or the like. 
   As is apparent from  FIG. 4 , a non-magnetic layer  45  of a constant thickness is interposed between the lower magnetic pole  34  of the thin film magnetic head  32  and the upper shield layer  43  of the read head  42  in the read/write electromagnetic transducer  23 . The non-magnetic layer  45  serves to space the lower magnetic pole  34  from the upper shield layer  43 . The non-magnetic layer may be made of Al 2 O 3 , for example. Otherwise, the lower magnetic pole  34  of the thin film magnetic head  32  may also function as the upper shield layer  43  of the read head  42 . 
   When an electric current is supplied to the swirly coil pattern  31  in the thin film magnetic head  32 , a magnetic field is induced at the swirly coil pattern  31 . The magnetic flux is introduced to the upper and lower magnetic poles  34 ,  35  from the central position of the swirly coil pattern  31 . The magnetic flux is exchanged between the upper and lower magnetic poles  34 ,  35 . The non-magnetic layer  37  and the non-magnetic substratum  38  serve to allow the exchanged magnetic flux to get leaked from the air bearing surface  28 . The leaked magnetic flux forms a magnetic field for recording at the bottom surface  25 . The formed magnetic field is utilized to magnetize the magnetic recording disk  13  opposed to the bottom surface  25  in predetermined directions. 
   In particular, a higher saturation magnetic flux density can be obtained at the front end of the upper magnetic pole  35  in the thin film magnetic head  32 . A stronger magnetic field for recording can accordingly be formed at the write gap of the thin film magnetic head  32 . A stronger magnetic field for recording of the thin film magnetic head  32  enables utilization of a material having a higher coercivity for the magnetic recording disk  13 . As a result, an increased number of recording tracks can be established for a unit area over the magnetic recording disk  13 . The recording density can thus be improved. 
   Next, a brief description will be made on a method of making the thin film magnetic head  32 . The upper and lower shield layers  43 ,  44  as well as the magnetoresistive element  41 , embedded within an Al 2 O 3  film interposed between the upper and lower shield layers  43 ,  44 , for example, are formed on a wafer, not shown, made of Al 2 O 3 —TiC in a conventional manner. As shown in  FIG. 5 , the magnetoresistive element  41  is finally subjected to abrasion up to a datum plane  51 . A marginal section  52  is removed based on the abrasion. The abrasion serves to allow the magnetoresistive element  41  to get exposed at the datum plane  51 , namely, the air bearing surface  28 . 
   The lower magnetic pole  34  and the swirly coil pattern  31  are formed on the upper shield layer  43 . A flattening polishing process may be employed to expose the top surfaces of the front and rear magnetic pole pieces  34   b ,  34   c  at the flat surface  36 . The non-magnetic layer  37  and the non-magnetic substratum  38  are sequentially formed on the flat surface  36 , as shown in  FIG. 6 , for example. Sputtering may be employed to form the non-magnetic layer  37  and the non-magnetic substratum  38 . A swelling  53  of a non-magnetic material such as Al 2 O 3  is then formed to extend over the non-magnetic substratum  38 . A photoresist film  54  is thereafter formed to spread over the swelling  53  and the non-magnetic substratum  38 . A void  55  is defined in the photoresist film  54 . The void  55  is designed to correspond to the shape of the upper magnetic pole  35 . 
   The ferromagnetic layer  35   a  is then formed within the void  55 . Sputtering may be employed to deposit the ferromagnetic layer  35   a . The target of the sputtering may comprise any alloy selected from FeCo, FeCoN, FeCoAlO, or other FeCo-based alloy, for example. Employment of a so-called revolving deposition serves to establish the easy axis of magnetization along the direction of the revolution in the ferromagnetic layer  35   a  deposited on the non-magnetic substratum  38 . 
   As shown in  FIG. 7 , when the revolving deposition is conducted, a wafer  56 , namely, the non-magnetic substratum  38  is set on a rotary support  57 , for example. When the rotary support  57  rotates, the non-magnetic substratum  38  is allowed to move along the circular orbit. As is apparent from  FIG. 8 , a through hole  59  defined in a shielding plate  58  serves to allow the particles or atoms to be sputtered out of the target  61  every time the non-magnetic substratum  38  passes right below the target  61 . The particles or atoms are deposited on the non-magnetic substratum  38  as well as the swelling  53  within the void  55 . The easy axis  ES  of magnetization is established along the direction of the movement in the ferromagnetic layer  35   a  on the non-magnetic substratum  38 . A soft magnetic property is in this manner established in the ferromagnetic layer  35   a  on the non-magnetic substratum  38 . 
   The primary magnetic pole layer  35   b  is formed on the ferromagnetic layer  35   a  within the void  55 . Sputtering may be employed to form the primary magnetic pole layer  35   b , for example. The upper magnetic pole  35  is thus formed to extend from the central position of the swirly coil pattern  31  to the datum plane  51  within the void  55 . 
   As shown in  FIG. 9 , a trimming process is then effected on the upper magnetic pole  35 . The trimming process requires a photoresist film  63  formed on the upper magnetic pole  35 . Ion milling, for example, is employed to engrave the upper magnetic pole  35   a ,  35   b , the non-magnetic substratum  38 , the non-magnetic layer  37  and the lower magnetic pole  34  in narrower forms. The thin film magnetic head  32  has been established on the wafer in the aforementioned manner. A non-magnetic film such as an Al 2 O 3  film may finally be formed to cover over the thin film magnetic head  32 . When the marginal section  52  is removed in the aforementioned manner, the formation of the thin film magnetic head  32  has been completed. 
   The inventors have observed the magnetic characteristic of the aforementioned ferromagnetic layer  35   a . In the observation, the inventors have prepared the non-magnetic substratum or substructure based on NiFe alloy. Non-magnetic Cr atoms are added to the NiFe alloy so as to establish a non-magnetic property of the NiFe alloy. As shown in  FIG. 10 , it has been confirmed that the complete non-magnetic property appears in the NiFe alloy if the Cr atoms are added to the NiFe alloy at a content equal to or larger than 25 at %. A vibration sampling magnetometer (VSM) is employed to measure the saturation magnetic flux density  Bs . The NiFe alloy layer was placed within a magnetic field of 800 [kA/m]. 
   The inventors have also formed a ferromagnetic layer of Fe 68.6 Co 29.4 Al 0.4 O 1.6  alloy over a non-magnetic substratum of Ni 61 Fe 14 Cr 25  alloy based on the revolving deposition as described above. The non-magnetic substratum was formed on a Ti film of 5.0 nm thickness extending over the surface of a wafer made of glass. The thickness of the non-magnetic substratum was set at 2.0 nm. A sintered mass of the mixture of Fe 70 Co 30  powder and Al 2 O 3  powder was used as the target of sputtering for depositing the ferromagnetic layer. The content of the Al 2 O 3  powder was set in a range between 0.1–3.0 at % in the target. Sputtering was conducted under the atmosphere of Ar gas. The pressure within the chamber was set in a range between 0.1–1.0[Pa]. The applied electric power density was set in a range between 1.0×10 −4 –10.0×10 −4  [W/m 2 ]. The wafer was spaced from the target by the distance of 90–180 mm. The ferromagnetic layer of 300 nm thickness was formed over the non-magnetic substratum. The wafer was kept cooled by water during the sputtering. The BH curve has been derived for the ferromagnetic layer of the FeCoAlO alloy laid over the non-magnetic substratum of the NiFeCr alloy. As is apparent from  FIG. 11 , the uniaxial magnetic anisotropy is surely established in the ferromagnetic layer of the FeCoAlO alloy. 
   The inventors have prepared two comparative examples of a ferromagnetic layer. The first comparative example included the ferromagnetic layer of the FeCoAlO, having the thickness of 300 nm, directly laid over the Ti film of 5.0 nm thickness. The second comparative example included the ferromagnetic layer of the FeCoAlO alloy, having the thickness of 300 nm, laid over a ferromagnetic substratum of Ni 80 Fe 20  alloy of 2.0 nm thickness formed over the Ti film of 5.0 nm thickness. As is apparent from  FIG. 12 , the magnetic isotropy was observed in the ferromagnetic layer of the first comparative example. It has been demonstrated that the non-magnetic substratum of the NiFeCr alloy serves to establish the uniaxial magnetic anisotropy in the ferromagnetic layer of the FeCoAlO alloy. On the other hand, the uniaxial magnetic anisotropy was observed in the ferromagnetic layer of the second comparative example as is apparent from  FIG. 13 . It has accordingly been demonstrated that even the non-magnetic substratum of the NiFe alloy serves to establish the uniaxial magnetic anisotropy in the ferromagnetic layer of the FeCoAlO alloy in accordance with the present invention in the same manner as the ferromagnetic substratum of the NiFe alloy. The establishment of the magnetic anisotropy in the ferromagnetic layer of the FeCoAlO alloy on the ferromagnetic substratum of the NiFe alloy is mentioned in IEEE Transactions on Magnetics, Vol. 36, No. 5, September 2000, pp2506–2508. 
   Next, the inventors have measured the saturation magnetic flux density  Bs  and the residual magnetic flux density  Br  for the ferromagnetic layer of the FeCoAlO alloy on the non-magnetic layer of the NiFeCr alloy. During the measurement,the inventors have changed the angle of the BH measurement. As is apparent from  FIG. 14 , the ratio of the saturation magnetic flux density  Bs  to the residual magnetic flux density  Br , namely, the maximum value of Bs/Br was obtained in the direction of the easy axis of magnetization. In addition, the minimum value of Bs/Br was obtained in the direction of the hard axis of magnetization. Thereafter, the inventors have applied a linear magnetic field to the ferromagnetic layer of the FeCoAlO alloy in the direction perpendicular to the easy axis of magnetization of the ferromagnetic layer of the FeCoAlO alloy. The intensity of the linear magnetic field was set at 240 [kA/m]. The ferromagnetic layer of the FeCoAlO alloy was placed under the high temperature condition of 280 degrees Celsius during the application of the linear magnetic field. The application of the linear magnetic field was maintained for three (3) hours. After the application of the linear magnetic field, the inventors measured the saturation magnetic flux density  Bs  and the residual magnetic flux density  Br  for the ferromagnetic layer of the FeCoAlO alloy on the non-magnetic layer of the NiFeCr alloy. As shown in  FIG. 15 , no change could be observed in the uniaxial magnetic anisotropy. It has been demonstrated that the aforementioned revolving deposition surely contributes to establishment of the uniaxial magnetic anisotropy in the ferromagnetic layer of the FeCoAlO alloy without the application of the linear magnetic field under the high temperature condition. 
   Furthermore, the inventors have formed a ferromagnetic layer of Fe 65 Co 35  alloy on the non-magnetic substratum of the Ni 61 Fe 14 Cr 25  alloy based on the revolving deposition in the manner as described above. The thickness of the ferromagnetic layer of the Fe 65 Co 35  alloy was set at 300 nm. The inventors have observed the BH curve for the ferromagnetic layer of the FeCo alloy on the non-magnetic substratum of the NiFeCr alloy. As shown in  FIG. 16 , the uniaxial magnetic anisotropy was observed in the ferromagnetic layer of the FeCo alloy. A higher saturation magnetic flux density such as 2.45[T] was maintained in the ferromagnetic layer of the FeCo alloy. 
   In this case, the inventors prepared a ferromagnetic layer of a comparative example. The ferromagnetic layer of the FeCo alloy having 300 nm thickness was formed directly on the Ti film of the 5.0 nm thickness. As shown in  FIG. 17 , the magnetic isotropy was observed in the ferromagnetic layer of the comparative example. It has been demonstrated that the non-magnetic substratum of the NiFeCr layer surely contributes to establishment of the uniaxial magnetic anisotropy in the ferromagnetic layer of the FeCo alloy. It should be noted that the uniaxial magnetic anisotropy can be established in the ferromagnetic layer of the FeCo alloy on the non-magnetic layer of the NiFeCr alloy with or without the Ti film.