Magnetoresistance effect device and method of forming the same as well as magnetoresistance effect sensor and magnetic recording system

The present invention provides a multilayer structure comprising: one of a first antiferromagnetic layer and a bias ferromagnetic layer; an interface control layer in contact with the one of the first antiferromagnetic layer and the bias ferromagnetic layer; a free magnetic layer in contact with the interface control layer; a non-magnetic layer in contact with the free magnetic layer; a pinned magnetic layer in contact with the non-magnetic layer; and a second ferromagnetic layer in contact with the pinned magnetic layer.

BACKGROUND OF THE INVENTION
 The present invention relates to a magnetoresistance effect device having a
 spin value structure for utilizing a variation in electrical resistance
 caused by relationships in variation of both a magnetization direction of
 a pinned layer and a magnetization direction of a free layer effected by
 an externally applied magnetic field, and a method of forming the same as
 well as a magnetoresistance effect sensor and a magnetic recording system.
 The magnetoresistance effect sensor or the magnetoresistance effect head
 are useful for reading data from a magnetic surface at a large linear
 density. The magnetoresistance effect sensor detects magnetic signals
 based upon variations in intensity and direction of a detected magnetic
 flux.
 The conventional magnetoresistance effect sensor is operated based upon an
 anisotropic magnetoresistance effect where one component of a resistance
 of the reading device varies in proportional to squares of cosine of an
 angle between a magnetization direction and a defecting current direction
 flowing through the device. This anisotropic magnetoresistance effect is
 disclosed in detail in literature IEEE Trans. On Mag. MAG-11, p. 1039,
 1975 "D. A. Thomson et al. Memory Storage and Related Application".
 In recent years, remarkable magnetoresistance effects have been reported
 such as a giant magnetoresistance effect and a spin valve effect, wherein
 the variation in resistance of the magnetic sensor is caused by a spin
 dependent conductivity of conductive electrons between two magnetic layers
 sandwiching a non-magnetic intermediate layer and by a spin dependent
 scattering phenomenon on interfaces thereof.
 Those magnetoresistance effect sensors utilizing the giant
 magnetoresistance effect or the spin valve effect show higher
 sensitivities or larger variations in resistance than the conventional
 sensors utilizing the anisotropic magnetoresistance effect. The giant
 magnetoresistance effect sensor or the spin valve effect sensor utilizes
 the phenomenon that in-plane resistances of the paired ferromagnetic
 layers sandwiching the non-magnetic layer vary in proportional to cosine
 of an angle between the magnetization directions of the paired
 ferromagnetic layers.
 In Japanese laid-open patent publication No. 2-61572, it is disclosed that
 an antiparallel magnetization causes the big variation in
 magnetoresistance of the magnetic layered structure. Available materials
 for the magnetic layered structure are ferromagnetic transition metals and
 ferromagnetic alloys. Further, it is possible to add an antiferromagnetic
 layer on one of the paired ferromagnetic layers sandwiching the
 non-magnetic layer. FeMn is suitable for the antiferromagnetic layer.
 In Japanese laid-open patent publication No. 4-358310, it is disclosed that
 no applied magnetic field to the two thin ferromagnetic layers sandwiching
 the non-magnetic layer causes that the magnetization directions of the two
 ferromagnetic layers are perpendicular to each other. A resistance between
 two non-coupled ferromagnetic layers varies in proportional to cosine of
 the angle of the magnetization directions of those two layers, so that the
 magnetoresistance effect sensor shows sensing operation independently from
 the direction of the current flowing through the sensor.
 In Japanese laid-open patent publication No. 6-203340, it is disclosed that
 two thin ferromagnetic layers are provided which sandwich the non-magnetic
 thin film and if no external magnetic field is zero, a magnetization
 direction of an adjacent antiferromagnetic layer is kept in
 perpendicularly to a magnetization direction of other ferromagnetic layer.
 In order to reduce a noise of the magnetoresistance effect sensor, it is
 important that the variation of the magnetization direction of the free
 layer due to an externally applied magnetic field is continuous without,
 however, any hysteresis, for which reason an effective external magnetic
 field is applied to the free magnetic layer to form a single magnetic
 domain.
 In Japanese laid-open patent publication No. 9-73611, it is disclosed that
 an antiferromagnetic layer is positioned under a free magnetic layer so
 that the antiferromagnetic layer is securely contact with the free layer
 in opposite sides regions defined with predetermined track regions so as
 to order the magnetization directions of the free layer. In the free layer
 adhered with the antiferromagnetic layer, an exchange-coupling magnetic
 field is generated thereby fixing the magnetization direction of the free
 layer securely in contact with the antiferromagnetic layer. The fixed
 portion and the continuously varied portion of the free layer are also
 made into single magnetic domain.
 FIG. 1 is a fragmentary cross sectional elevation view illustrative of a
 lamination structure of a conventional magnetoresistance effect sensor. An
 externally applied magnetic field to the magnetoresistance effect sensor
 is directed in an X-direction. This lamination structure is as follows. A
 bottom gap layer 32 is laminated on a substrate 31. A base layer 33 is
 laminated on the bottom gap layer 32. A free magnetic layer 34 is
 laminated on the base layer 33. A non-magnetic layer 35 is also laminated
 on the free magnetic layer 34. A pinned magnetic layer 36 is also
 laminated on the non-magnetic layer 35. An antiferromagnetic layer 37 is
 also laminated on the pinned magnetic layer 36.
 For the magnetoresistance effect sensor utilizing the spin valve, it is
 necessary that the magnetization direction of the pinned layer is fixed by
 the antiferromagnetic layer. Generally, Fe--Mn, NiO, Ni--Mn, Pt--Mn alloys
 are available. FeMn and NiO are advantageous in easy formation but
 disadvantages in low thermal stability due to a low blocking temperature
 of 200.degree. C.
 The antiferromagnetic layer is made of an alloy such as Ni--Mn alloy which
 has a relatively high blocking temperature of not less than 200.degree. C.
 whereby the antiferromagnetic layer has a high thermal stability. However,
 in order to cause the exchange-coupling magnetic field directed in a
 predetermined direction, it is necessary to carry out a heat treatment in
 the magnetic field. This heat treatment in the magnetic field provides an
 influence to the magnetic anisotropy of the free magnetic layer whereby a
 hysteresis appears on an R-H curve or an electric resistance-magnetic
 filed curve. As a result, noises are generated in the measurement of the
 magnetic field.
 In the above circumstances, it had been required to develop a novel
 magnetoresistance effect sensor free from the above problems and a method
 of forming the same as well as a magnetic recording system.
 SUMMARY OF THE INVENTION
 Accordingly, it is an object of the present invention to provide a novel
 magnetoresistance effect sensor free from the above problems.
 It is a further object of the present invention to provide a novel
 magnetoresistance effect sensor with a high thermal stability.
 It is a still further object of the present invention to provide a novel
 magnetoresistance effect sensor with reduced noises in measurement to
 magnetic fields.
 It is yet a further object of the present invention to provide a novel
 method of forming a magnetoresistance effect sensor free from the above
 problems.
 It is a further more object of the present invention to provide a novel
 method of forming a magnetoresistance effect sensor with a high thermal
 stability.
 It is still more object of the present invention to provide a novel method
 of forming a magnetoresistance effect sensor with reduced noises in
 measurement to magnetic fields.
 It is moreover object of the present invention to provide a novel magnetic
 recording system utilizing a magnetoresistance effect sensor free from the
 above problems.
 It is another object of the present invention to provide a novel magnetic
 recording system utilizing a magnetoresistance effect sensor with a high
 thermal stability.
 It is still another object of the present invention to provide a novel
 magnetic recording system utilizing a magnetoresistance effect sensor with
 reduced noises in measurement to magnetic fields.
 The present invention provides a multilayer structure comprising: one of a
 first antiferromagnetic layer and a bias ferromagnetic layer; an interface
 control layer in contact with the one of the first antiferromagnetic layer
 and the bias ferromagnetic layer; a free magnetic layer in contact with
 the interface control layer; a non-magnetic layer in contact with the free
 magnetic layer; a pinned magnetic layer in contact with the non-magnetic
 layer; and a second ferromagnetic layer in contact with the pinned
 magnetic layer, so that a magnetic anisotropy of the free magnetic layer
 is made directed to a parallel direction to interfaces of the multilayer
 structure due to an exchange coupling magnetic field of the one of the
 first antiferromagnetic layer and the bias ferromagnetic layer, and that a
 magnetic anisotropy of the pinned magnetic layer is made directed to a
 vertical direction to the interfaces of the multilayer structure due to an
 exchange coupling magnetic field of the second antiferromagnetic layer.
 The above and other objects, features and advantages of the present
 invention will be apparent from the following descriptions.

DISCLOSURE OF THE INVENTION
 The first present invention provides a multilayer structure comprising: one
 of a first antiferromagnetic layer and a bias ferromagnetic layer; an
 interface control layer in contact with the one of the first
 antiferromagnetic layer and the bias ferromagnetic layer; a free magnetic
 layer in contact with the interface control layer; a non-magnetic layer in
 contact with the free magnetic layer; a pinned magnetic layer in contact
 with the non-magnetic layer; and a second ferromagnetic layer in contact
 with the pinned magnetic layer.
 It is preferable that a magnetic anisotropy of the free magnetic layer is
 made directed to a parallel direction to interfaces of the multilayer
 structure due to an exchange coupling magnetic field of the one of the
 first antiferromagnetic layer and the bias ferromagnetic layer, and that a
 magnetic anisotropy of the pinned magnetic layer is made directed to a
 vertical direction to the interfaces of the multilayer structure due to an
 exchange coupling magnetic field of the second antiferromagnetic layer.
 It is also preferable that a first blocking temperature TB1 as a maximum
 temperature for generating an exchange coupling magnetic field of the
 first antiferromagnetic layer and a second blocking temperature TB2 as a
 maximum temperature for generating an exchange coupling magnetic field of
 second antiferromagnetic layer satisfy the following equations:
EQU TB1&gt;150.degree. C. and .vertline.TB2-TB1.vertline.&gt;50.degree. C.
 It is also preferable that a first exchange coupling magnetic field Hex1 of
 the one of the first antiferromagnetic layer and the bias ferromagnetic
 layer and a second exchange coupling magnetic field Hex2 of the second
 antiferromagnetic layer satisfy the following equations:
EQU Hex1&gt;10 Oe and Hex2&gt;200 Oe.
 It is also preferable that at least one of the first and second
 antiferromagnetic layers includes at least one of alpha-Fe.sub.2 O.sub.3,
 NiO, Fc--Mn alloy, Ni--Mn alloy, Pt--Mn alloy, Ir--Mn alloy, Rh--Mn alloy,
 Ru--Mn alloy, and Cr--Al alloy.
 It is further preferable that at least one of the first and second
 antiferromagnetic layers includes an alloy of at least two of
 alpha-Fe.sub.2 O.sub.3, NiO, Fe--Mn alloy, Ni--Mn alloy, Pt--Mn alloy,
 Ir--Mn alloy, Rh--Mn alloy, Ru--Mn alloy, and Cr--Al alloy.
 It is also preferable that at least one of the first and second
 antiferromagnetic layers has double layers, each of which includes at
 least one of alpha-Fe.sub.2 O.sub.3, NiO, Fe--Mn alloy, Ni--Mn alloy,
 Pt--Mn alloy, Ir--Mn alloy, Rh--Mn alloy, Ru--Mn alloy, and Cr--Al alloy.
 It is further preferable that the each of the double layers includes an
 alloy of at least two of alpha-Fe.sub.2 O.sub.3, NiO, Fe--Mn alloy, Ni--Mn
 alloy, Pt--Mn alloy, Ir--Mn alloy, Rh--Mn alloy, Ru--Mn alloy, and Cr--Al
 alloy.
 It is also preferable that the interface control layer includes at least
 one of Al, Ti, V, Cr, Mn, Cu, Zn, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Hf, Ta,
 W, Re, Pt, Au, Pb, Bi, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, and
 oxides thereof, and alloys thereof.
 It is further preferable that the interface control layer includes at least
 one of oxides of Fe, Ni and Co and double oxides thereof.
 It is also preferable that a thickness "t" of the interface control layer
 satisfy the following equation: 1 nm.ltoreq.t.ltoreq.10 nm.
 It is also preferable that at least one of the free magnetic layer and the
 pinned magnetic layer includes at least one of Co, Fe, Ni and alloys
 thereof.
 It is also preferable that at least one of the free magnetic layer and the
 pinned magnetic layer has an interface layered region with the
 non-magnetic layer and the interface layered region comprises one of Co
 and Co--Fe.
 The above novel multilayer structure of the first present invention is
 applicable to a magnetoresistaace effect element.
 The magnetoresistance effect element having the above novel multilayer
 structure of the first present invention is also applicable to a
 magnetoresistance effect sensor comprising: a substrate; a bottom magnetic
 shield layer on the substrate; a bottom gap layer on the bottom magnetic
 shield layer; the above novel magnetoresistance effect element on the
 bottom gap layer; an electrode layer on a part of the magnetoresistance
 effect element; a top gap layer on both the electrode layer and the
 magnetoresistance effect element; and a top magnetic shield layer on the
 top gap layer.
 It is preferable that the electrode layer is in contact with an edge of the
 magnetoresistance effect element.
 It is also preferable that the electrode layer comprises first and second
 electrodes which are distanced from each other and provided on opposite
 side regions of the magnetoresistance effect element.
 The above novel magnetoresistance effect sensor is also applicable to a
 magnetic recording system comprising: a magnetic recording medium having a
 plurality of tracks for recording data; a magnetic transducer having a
 magnetic detector of the above novel magnetoresistance effect sensor for
 detecting variation in magnetoresistance based upon a magnetic field
 generated from data stored in the magnetic recording medium; and an
 actuator mechanically connected to the magnetic transducer for moving the
 magnetic transducer over a surface of the magnetic recording medium.
 A magnetic field is externally applied to the above magnetoresistance
 effect sensor in a track width direction parallel to interfaces of the
 multilayer structure of the magnetoresistance effect sensor, during which
 the magnetoresistance effect sensor is subjected to a heat treatment at a
 temperature of not less than a first blocking temperature TB1 of the first
 antiferromagnetic layer.
 In order to realize a high power output and low noise property of the
 magnetoresistance effect sensor utilizing the spin valve phenomenon, it is
 important that the magnetic anisotropy of the free magnetic layer is
 directed in a track width direction or a parallel direction to interfaces
 of the multilayer structure due to an exchange coupling magnetic field of
 the one of the first antiferromagnetic layer and the bias ferromagnetic
 layer. It is also important that that a magnetic anisotropy of the pinned
 magnetic layer is made directed to a vertical direction to the interfaces
 of the multilayer structure due to an exchange coupling magnetic field of
 the second antiferromagnetic layer. The noises are co-related with the
 magnetic anisotropy of the free magnetic layer which shows variation in
 magnetization direction due to an externally applied magnetic field.
 When the magnetic anisotropy of the free magnetic layer is directed to the
 vertical direction to the interfaces of the multilayer structure of the
 magnetoresistance effect element, the direction of the magnetic anisotropy
 is parallel to the direction of the externally applied magnetic field,
 whereby a movement of the magnetization direction is the magnetic domain
 movement mode which shows a hysteresis.
 When the magnetic anisotropy of the free magnetic layer is directed to the
 parallel direction to the interfaces of the multilayer structure of the
 magnetoresistance effect element, the direction of the magnetic anisotropy
 is perpendicular to the direction of the externally applied magnetic
 field, whereby a movement of the magnetization direction is the magnetic
 domain rotation mode which shows no hysteresis.
 The magnetic anisotropy of the free magnetic layer is an inductive magnetic
 anisotropy inductive by a magnetic field in the deposition of the free
 magnetic layer. This magnetic anisotropy of the free magnetic layer varies
 in direction by subjecting the free magnetic layer to a heat treatment at
 a temperature of at a temperature of not less than 200.degree. C. which is
 necessary for causing an exchange-coupling magnetic field in the pinned
 magnetic layer during an external application of a magnetic field to the
 magnetoresistance effect element.
 The pinned magnetic layer is subjected to the heat treatment in the
 magnetic field in the essential process for forming the magnetoresistance
 effect sensor utilizing the spin valve effect. This heat treatment in the
 magnetic field causes the magnetic anisotropy to be directed to the
 vertical direction to the interfaces of the multilayer structure of the
 magnetoresistance effect element. This magnetic anisotropy directed to the
 vertical direction causes noises to the magnetoresistance effect sensor.
 In order to cause the magnetic anisotropy of the free magnetic layer to be
 directed in perpendicular to the fixed magnetic anisotropy of the pinned
 magnetic layer without rotation of the magnetic anisotropy of the pinned
 magnetic layer, it is necessary to rotate the magnetic anisotropy of the
 free magnetic layer at a temperature lower by at least 50.degree. C. than
 the temperature of the heat treatment to the pinned magnetic layer.
 Contact of the entire surface of the antiferromagnetic layer or the large
 coercive ferromagnetic layer with the free magnetic layer enables
 effecting the free magnetic layer with a larger exchange coupling magnetic
 field than the inductive magnetic anisotropy. The sensitivity of the
 magnetoresistance effect sensor depends upon the magnitude of the exchange
 coupling magnetic field. The control in the magnitude of the exchange
 coupling magnetic field is extremely important. The insertion of the
 interface control layer comprising the thin non-magnetic metal layer
 between the antiferromagnetic layer and the ferromagnetic layer enables
 control of the magnitude of the exchange coupling magnetic field.
 Accordingly, in accordance with the present invention, the novel multilayer
 structure of the magnetoresistance effect element comprises: one of a
 first antiferromagnetic layer and a bias ferromagnetic layer; an interface
 control layer in contact with the one of the first antiferromagnetic layer
 and the bias ferromagnetic layer; a free magnetic layer in contact with
 the interface control layer; a non-magnetic layer in contact with the free
 magnetic layer; a pinned magnetic layer in contact with the non-magnetic
 layer; and a second ferromagnetic layer in contact with the pinned
 magnetic layer, wherein a magnetic anisotropy of the free magnetic layer
 is made directed to a parallel direction to interfaces of the multilayer
 structure due to an exchange coupling magnetic field of the one of the
 first antiferromagnetic layer and the bias ferromagnetic layer, and that a
 magnetic anisotropy of the pinned magnetic layer is made directed to a
 vertical direction to the interfaces of the multilayer structure due to an
 exchange coupling magnetic field of the second antiferromagnetic layer.
 The thickness "t" of the interface control layer satisfies the following
 equation: 1 nm.ltoreq.t.ltoreq.10 nm so that the magnitude of the exchange
 coupling magnetic field is suitable for the magnetoresistance effect
 sensor.
 If the bias ferromagnetic layer is used, a magnetic field larger than a
 coercive force of the bias ferromagnetic layer is applied in the track
 width direction parallel to the interfaces of the multilayer structure of
 the magnetoresistance effect, so that the magnetic anisotropy effected to
 the free magnetic layer is directed to the track width direction parallel
 to the interfaces of the multilayer structure of the magnetoresistance
 effect, whereby the variation of the magnetization direction is free from
 hysteresis.
 The blocking temperature TB1 of the free magnetic layer is lowered by
 50.degree. C. Than the temperature of the heat treatment to the pinned
 magnetic layer with application of the magnetic field, so that the
 magnetic field is applied in the track width direction parallel to the
 interfaces of the multilayer structure of then magnetoresistance effect,
 whereby the anisotropic direction of the pinned magnetic layer is kept in
 the original direction whilst the anisotropic direction of the free
 magnetic layer is made directed in perpendicular to the anisotropic
 direction of the pinned magnetic layer.
 The magnetic disk has an operational temperature of about 100.degree. C.,
 for which reason in order to obtain a performance stability of the
 magnetic disk, it is necessary that the first blocking temperature TB1 as
 a maximum temperature for generating an exchange coupling magnetic field
 of the first antiferromagnetic layer satisfies TB1&gt;150.degree. C. It is
 also necessary that the first exchange coupling magnetic field Hex1 of the
 one of the first antiferromagnetic layer is sufficiently larger than the
 inductive magnetic anisotropy of the free magnetic layer. It is preferable
 that Hex1&gt;10 Oe.
 FIG. 2 is a fragmentary cross sectional elevation view illustrative of the
 above novel magnetoresistance effect sensor in accordance with the present
 invention, wherein an external magnetic field is applied in an X-direction
 to the novel magnetoresistance effect sensor. The novel magnetoresistance
 effect sensor is formed on a substrate 11. A bottom gap layer 12 is
 provided on the substrate 11. A base layer 13 is provided on the bottom
 gap layer 12. A first antiferromagnetic layer 14 is provided on the base
 layer 13. An interface control layer 15 is provided on the first
 antiferromagnetic layer 14. A free magnetic layer 16 is provided on the
 interface control layer 15. A non-magnetic layer 17 is provided on the
 free magnetic layer 16. A pinned magnetic layer 18 is provided on the
 non-magnetic layer 17. A second antiferromagnetic layer 19 is provided on
 the pinned magnetic layer 18. Electrode layers 20 are provided on outside
 regions on the second ferromagnetic layer 19 so as to avoid a magnetic
 field detecting region 21 of the second ferromagnetic layer 19. A current
 source 22 is connected between the electrode layers 20. A detector 23 is
 also connected between the electrode layers 20.
 Each of the first and second antiferromagnetic layers 14 and 19 comprises
 at least one of alpha-Fe.sub.2 O.sub.3, NiO, Fe--Mn alloy, Ni--Mn alloy,
 Pt--Mn alloy, Ir--Mn alloy, Rh--Mn alloy, Ru--Mn alloy, and Cr--Al alloy,
 or comprises an alloy of at least two of alpha-Fe.sub.2 O.sub.3, NiO,
 Fe--Mn alloy, Ni--Mn alloy, Pt--Mn alloy, Ir--Mn alloy, Rh--Mn alloy,
 Ru--Mn alloy, and Cr--Al alloy. Each of the first and second
 antiferromagnetic layers 14 and 19 may comprise double layers, each of
 which includes at least one of alpha-Fe.sub.2 O.sub.3, NiO, Fe--Mn alloy,
 Ni--Mn alloy, Pt--Mn alloy, Ir--Mn alloy, Rh--Mu alloy, Ru--Mn alloy, and
 Cr--Al alloy. Each of the double layers may comprise an alloy of at least
 two of alpha-Fe.sub.2 O.sub.3, NiO, Fe--Mn alloy, Ni--Mn alloy, Pt--Mn
 alloy, Ir--Mn alloy, Rh--Mn alloy, Ru--Mn alloy, and Cr--Al alloy.
 The interface control layer 15 comprises at least one of Al, Ti, V, Cr, Mn,
 Cu, Zn, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Hf, Ta, W, Re, Pt, Au, Pb, Bi, La,
 Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, and oxides thereof, and alloys
 thereof, or comprises at least one of oxides of Fe, Ni and Co and double
 oxides thereof.
 Each of the free magnetic layer 16 and the pinned magnetic layer 18
 comprises at least one of NiFe-based materials, NiFeCo-based materials,
 CoZr-based materials, NiFeB-based materials, Sendust, FeN-based materials
 and FeCo. Each of the free magnetic layer 16 and the pinned magnetic layer
 18 as well as the non-magnetic layer 17 may be adjacent to a thin layer of
 one of Co and Co--Fe. The non-magnetic layer may comprise Au, Ag, Cu and
 alloys thereof.
 The above novel magnetoresistance effect sensor is also applicable to a
 magnetic recording system comprising: a magnetic recording medium having a
 plurality of track for recording data; a magnetic transducer having a
 magnetic detector of the above novel magnetoresistance effect sensor for
 detecting variation in magnetoresistance based upon a magnetic field
 generated from data stored in the magnetic recording medium; and an
 actuator mechanically connected to the magnetic transducer for moving the
 magnetic transducer over a surface of the magnetic recording medium.
 FIG. 3 is a diagram illustrative of an R-H curve of the magnetoresistance
 effect element utilizing the spin valve effect and comprising the first
 novel multilayer structure, wherein the first antiferromagnetic layer is
 made of NiO and has a thickness of 30 nanometers and the interface control
 layer is made of Cu and has a thickness of 1 nanometer. Namely, the first
 antiferromagnetic layer is made of NiO and has a thickness of 30
 nanometers. The interface control layer on the first antiferromagnetic
 layer is made of Cu and has a thickness of 1 nanometer. The free magnetic
 layer on the interface control layer is made of NiFe and has a thickness
 of 8 nanometers. The non-magnetic layer on the free magnetic layer is made
 of Cu and has a thickness of 2.5 nanometers. The pinned magnetic layer on
 the non-magnetic layer is made of CoPc and has a thickness of 3
 nanometers. The second antiferromagnetic layer on the pinned magnetic
 layer is made of NiMn and has a thickness of 30 nanometers.
 The NiO first antiferromagnetic layer is deposited by a radio frequency
 sputtering method with use of a sintered target and an Ar sputtering gas
 under a gas pressure of 0.3 Pa with a power of 200 W. The Cu interface
 control layer and the Cu non-magnetic layer are deposited by a DC
 magnetron sputtering method with use of an Ar sputtering gas under a gas
 pressure of 0.3 Pa with a power of 7 W. The NiFe non-magnetic layer and
 the CoFe pinned magnetic layer are also deposited by a DC magnetron
 sputtering method with use of an Ar sputtering gas under a gas pressure of
 0.3 Pa with a power of 35 W. The NiMn second antiferromagnetic layer is
 deposited by a radio frequency sputtering method with use of an alloy
 target and an Ar sputtering gas under a gas pressure of 0.3 Pa with a
 power of 100 W.
 The prepared multilayer structure is first subjected to a polarizing
 process to the pinned magnetic layer, for example, a heat treatment at a
 temperature of 270.degree. C. with application of a magnetic field of 3
 kOe in the vertical direction to the interfaces of the multilayer
 structure for 5 hours. Subsequently, the multilayer structure is then
 subjected to another polarizing process to the free magnetic layer, for
 example, a heat treatment at a temperature of 200.degree. C. with
 application of a magnetic field of 50 kOe in the parallel direction to the
 interfaces of the multilayer structure for 1 minute. The multilayer
 structure is then shaped to a size of 1 micrometer by 1 micrometer. Metal
 electrodes are provided thereon.
 This magnetoresistance element shows a normal magnetoresistance curve or
 R-H curve free of any hysteresis. If no polarizing process to the free
 magnetic layer is carried out, then the magnetoresistance element shows
 abnormal magnetoresistance curve or R-H curve with a remarkable
 hysteresis.
 FIG. 4 is a diagram illustrative of an R-H curve of the magnetoresistance
 effect element utilizing the spin valve effect and having no first
 antiferromagnetic layer and also no interface control layer. This
 magnetoresistance element shows abnormal magnetoresistance curve or R--H
 curve with a remarkable hysteresis.
 FIG. 5 is a diagram illustrative of an R-H curve of the magnetoresistance
 effect element utilizing the spin valve effect and having no interface
 control layer. This magnetoresistance element shows a normal
 magnetoresistance curve or R-H curve without any hysteresis. The
 exchange-coupling magnetic field is, however, large whereby the
 sensitivity is low and the output from the sensor is small.
 Another magnetoresistance effect element is prepared, wherein the first
 antiferromagnetic layer is made of FcMu and has a thickness of 10
 nanometers and the interface control layer is made of Ag and has a
 thickness of 1 nanometer. Namely, the first antiferromagnetic layer is
 made of FeMn and has a thickness of 10 nanometers. The interface control
 layer on the first antiferromagnetic layer is made of Ag and has a
 thickness of 1 nanometer. The free magnetic layer on the interface control
 layer is made of NiFe and has a thickness of 8 nanometers. The
 non-magnetic layer on the free magnetic layer is made of Cu and has a
 thickness of 2.5 nanometers. The pinned magnetic layer on the non-magnetic
 layer is made of CoFe and has a thickness of 3 nanometers. The second
 antiferromagnetic layer on the pinned magnetic layer is made of NiNon and
 has a thickness of 30 nanometers.
 The FeMn first antiferromagnetic layer is deposited by a radio frequency
 sputtering method with use of an alloy target and an Ar sputtering gas
 under a gas pressure of 0.3 Pa with a power of 100 W. The Ag interface
 control layer and the Cu non-magnetic layer are deposited by a DC
 magnetron sputtering method with use of an Ar sputtering gas under a gas
 pressure of 0.3 Pa with a power of 7 W. The NiFe non-magnetic layer and
 the CoFe pinned magnetic layer are also deposited by a DC magnetron
 sputter method with use of an Ar sputtering gas under a gas pressure of
 0.3 Pa with a power of 35 W. The NiMn second antiferromagnetic layer is
 deposited by a radio frequency sputtering method with use of an alloy
 target and an Ar sputtering gas under a gas pressure of 0.3 Pa with a
 power of 100 W.
 The prepared multilayer structure is first subjected to a polarizing
 process to the pinned magnetic layer, for example, a heat treatment at a
 temperature of 270.degree. C. with application of a magnetic field of 3
 kOe in the vertical direction to the interfaces of the multilayer
 structure for 5 hours. Subsequently, the multilayer structure is then
 subjected to another polarizing process to the free magnetic layer, for
 example, a heat treatment at a temperature of 150.degree. C. with
 application of a magnetic field of 50 kOe in the parallel direction to the
 interfaces of the multilayer structure for 1 minute. The multilayer
 structure is then shaped to a size of 1 micrometer by 1 micrometer. Metal
 electrodes are provided thereon.
 This magnetoresistance element shows a normal magnetoresistance curve or
 R-H curve free of any hysteresis.
 Still another magnetoresistance effect element is prepared, wherein the
 fist antiferromagnetic layer is made of alpha-Fe.sub.2 O.sub.3 and has a
 thickness of 30 nanometers and the interface control layer is made of Pb
 and has a thickness of 2 nanometers. Namely, the first antiferromagnetic
 layer is made of alpha-Fe.sub.2 O.sub.3 and has a thickness of 30
 nanometers. The interface control layer on the first antiferromagnetic
 layer is made of Pb and has a thickness of 2 nanometers. The free magnetic
 layer on the interface control layer is made of NiFe and has a thickness
 of 8 nanometers. The non-magnetic layer on the free magnetic layer is made
 of Cu and has a thickness of 2.5 nanometers. The pinned magnetic layer on
 the non-magnetic layer is made of CoFe and has a thickness of 3
 nanometers. The second antiferromagnetic layer on the pinned magnetic
 layer is made of NiMn and has a thickness of 30 nanometers.
 The alpha-Fe.sub.2 O.sub.3 first antiferromagnetic layer is deposited by a
 radio frequency sputtering method with use of a sintered target and an Ar
 sputtering gas under a gas pressure of 0.3 Pa with a power of 200 W. The
 Pb interface control layer and the Cu non-magnetic layer are deposited by
 a DC magnetron sputtering method with use of an Ar sputtering gas under a
 gas pressure of 0.3 Pa with a power of 7 W. The NiFe non-magnetic layer
 and the CoFe pinned magnetic layer are also deposited by a DC magnetron
 sputtering method with use of an Ar sputtering gas under a gas pressure of
 0.3 Pa with a power of 35 W. The NiMn second antiferromagnetic layer is
 deposited by a radio frequency sputtering method with use of an alloy
 target and an Ar sputtering gas under a gas pressure of 0.3 Pa with a
 power of 100 W.
 The prepared multilayer structure is first subjected to a polarizing
 process to the pinned magnetic layer, for example, a heat treatment at a
 temperature of 270.degree. C. with application of a magnetic field of 3
 kOe in the vertical direction to the interfaces of the multilayer
 structure for 5 hours. Subsequently, the multilayer structure is then
 subjected to another polarizing process to the free magnetic layer, for
 example, a heat treatment at a temperature of 180.degree. C. with
 application of a magnetic field of 50 kOe in the parallel direction to the
 interfaces of the multilayer structure for 1 minute. The multilayer
 structure is then shaped to a size of 1 micrometer by 1 micrometer. Metal
 electrodes are provided thereon.
 This magnetoresistance element shows a normal magnetoresistance curve or
 R-H curve free of any hysteresis.
 Yet another magnetoresistance effect element is prepared, wherein the first
 antiferromagnetic layer is made of Cr--Al and has a thickness of 30
 nanometers and the interface control layer is made of CrO.sub.2 and has a
 thickness of 2 nanometers. Namely, the first antiferromagnetic layer is
 made of Cr--Al and has a thickness of 30 nanometers. The interface control
 layer on the first antiferromagnetic layer is made of CrO.sub.2 and has a
 thickness of 3 nanometers. The free magnetic layer on the interface
 control layer is made of NiFe and has a thickness of 8 nanometers. The
 non-magnetic layer on the free magnetic layer is made of Cu and has a
 thickness of 2.5 nanometers. The pinned magnetic layer on the non-magnetic
 layer is made of CoFe and has a thickness of 3 nanometers. The second
 antiferromagnetic layer on the pinned magnetic layer is made of NiMn and
 has a thickness of 30 nanometers.
 The Cr--Al first antiferromagnetic layer is deposited by a radio frequency
 sputtering method with use of an alloy target and an Ar sputtering gas
 under a gas pressure of 0.3 Pa with a power of 100 W. The CrO.sub.2
 interface control layer and the Cu non-magnetic layer are deposited by a
 DC magnetron sputtering method with use of an Ar sputtering gas under a
 gas pressure of 0.3 Pa with a power of 7 W. The NiFe non-magnetic layer
 and the CoFe pinned magnetic layer are also deposited by a DC magnetron
 sputtering method with use of an Ar sputtering gas under a gas pressure of
 0.3 Pa with a power of 35 W. The NiMn second antiferromagnetic layer is
 deposited by a radio frequency sputtering method with use of an alloy
 target and an Ar sputtering gas under a gas pressure of 0.3 Pa with a
 power of 100 W.
 The prepared multilayer structure is first subjected to a polarizing
 process to the pinned magnetic layer, for example, a heat treatment at a
 temperature of 270.degree. C. with application of a magnetic field of 3
 kOe in the vertical direction to the interfaces of the multilayer
 structure for 5 hours. Subsequently, the multilayer structure is then
 subjected to another polarizing process to the free magnetic layer, for
 example, a heat treatment at a temperature of 220.degree. C. with
 application of a magnetic field of 50 kOe in the parallel direction to the
 interfaces of the multilayer structure for 1 minute. The multilayer
 structure is then shaped to a size of 1 micrometer by 1 micrometer. Metal
 electrodes are provided thereon.
 This magnetoresistance element shows a normal magnetoresistance curve or
 R-H curve free of any hysteresis.
 Further another magnetoresistance effect element is prepared, wherein the
 bias ferromagnetic layer is made of CoPt and has a thickness of 10
 nanometers and the interface control layer is made of CoO and has a
 thickness of 2 nanometers. Namely, the bias ferromagnetic layer is made of
 CoPt and has a thickness of 10 nanometers. The interface control layer on
 the bias ferromagnetic layer is made of CoO and has a thickness of 2
 nanometers. The free magnetic layer on the interface control layer is made
 of NiFe and has a thickness of 8 nanometers. The non-magnetic layer on the
 free magnetic layer is made of Cu and has a thickness of 2.5 nanometers.
 The pinned magnetic layer on the non-magnetic layer is made of CoFe and
 has a thickness of 3 nanometers. The second antiferromagnetic layer on the
 pinned magnetic layer is made of NiMn and has a thickness of 30
 nanometers.
 The CoPt bias ferromagnetic layer is deposited by a DC magnetron sputtering
 method with use of an alloy target and an Ar sputtering gas under a gas
 pressure of 0.3 Pa with a power of 100 W. The CoO interface control layer
 and the Cu non-magnetic layer are deposited by a DC magnetron sputtering
 method with use of an Ar sputtering gas under a gas pressure of 0.3 Pa
 with a power of 7 W. The NiFe non-magnetic layer and the CoFe pinned
 magnetic layer are also deposited by a DC magnetron sputtering method with
 use of an Ar sputtering gas under a gas pressure of 0.3 Pa with a power of
 35 W. The NiMn second antiferromagnetic layer is deposited by a radio
 frequency sputtering method with use of an alloy target and an Ar
 sputtering gas under a gas pressure of 0.3 Pa with a power of 100 W.
 The prepared multilayer structure is first subjected to a polarizing
 process to the pinned magnetic layer, for example, a heat treatment at a
 temperature of 270.degree. C. with application of a magnetic field of 3
 kOe in the vertical direction to the interfaces of the multilayer
 structure for 5 hours. Subsequently, the multilayer structure is then
 subjected to another polarizing process to the free magnetic layer, for
 example, a heat treatment at a room temperature with application of a
 magnetic field of 5 kOe in the parallel direction to the interfaces of the
 multilayer structure for 1 minute. The multilayer structure is then shaped
 to a size of 1 micrometer by 1 micrometer. Metal electrodes are provided
 thereon.
 This magnetoresistance element shows a normal magnetoresistance curve or
 R-H curve free of any hysteresis
 Further another magnetoresistance effect element is prepared, wherein the
 bias ferromagnetic layer is made of CoCrPt and has a thickness of 10
 nanometers and the interface control layer is made of Au and has a
 thickness of 1 nanometer Namely, the bias ferromagnetic layer is made of
 CoCrPt and has a thickness of 10 nanometers. The interface control layer
 on the bias ferromagnetic layer is made of Au and has a thickness of 1
 nanometer. The free magnetic layer on the interface control layer is made
 of NiFe and has a thickness of 8 nanometers. The non-magnetic layer on the
 free magnetic layer is made of Cu and has a thickness of 2.5 nanometers.
 The pinned magnetic layer on the non-magnetic layer is made of CoFe and
 has a thickness of 3 nanometers. The second antiferromagnetic layer on the
 pinned magnetic layer is made of NiMn and has a thickness of 30
 nanometers.
 The CoCrPt bias ferromagnetic layer is deposited by a DC magnetron
 sputtering method with use of an alloy target and an Ar sputtering gas
 under a gas pressure of 0.3 Pa with a power of 100 W. The Au interface
 control layer and the Cu non-magnetic layer are deposited by a DC
 magnetron sputtering method with use of an Ar sputtering gas under a gas
 pressure of 0.3 Pa with a power of 7 W. The NiFe non-magnetic layer and
 the CoFe pinned magnetic layer are also deposited by a DC magnetron
 sputtering method with use of an At sputtering gas under a gas pressure of
 0.3 Pa with a power of 35 W. The NiMa second antiferromagnetic layer is
 deposited by a radio frequency sputtering method with use of an alloy
 target and an Ar sputtering gas under a gas pressure of 0.3 Pa with a
 power of 100 W.
 The prepared multilayer structure is first subjected to a polarizing
 process to the pinned magnetic layer, for example, a heat treatment at a
 temperature of 270.degree. C. with application of a magnetic field of 3
 kOe in the vertical direction to the interfaces of the multilayer
 structure for 5 hours. Subsequently, the multilayer structure is then
 subjected to another polarizing process to the free magnetic layer, for
 example, a heat treatment at a room temperature with application of a
 magnetic field of 3 kOe in the parallel direction to the interfaces of the
 multilayer structure for 1 minute. The multilayer structure is then shaped
 to a size of 1 micrometer by 1 micrometer. Metal electrodes are provided
 thereon.
 This magnetoresistance element shows a normal magnetoresistance curve or
 R-H curve free of any hysteresis
 Whereas modifications of the present invention will be apparent to a person
 having ordinary skin in the art, to which the invention pertains, it is to
 be understood that embodiments as shown and described by way of
 illustrations are by no means intended to be considered in a limiting
 sense. Accordingly, it is to be intended to cover by claims all
 modifications which fall within the spirit and scope of the present
 invention.