Patent Application
20050122828
The present invention relates to a reproduction head for a magnetic recording device such as a magneto-optical disk, a hard disk, a digital data streamer (DDS) and a digital VTR, which are used for information communication terminals; an angular velocity magnetic sensor for sensing a rotation speed; a stress/acceleration sensor that senses a change in stress or acceleration; and a magnetoresistive sensor typified by a heat sensor or a chemical reaction sensor that utilizes a change in the magnetoresistive effect caused by heat or chemical reaction. The present invention also relates to a magnetic solid-state memory typified by a magnetic random access memory, a reconfigurable memory and the like; and a current switch (magnetic switch) device utilizing magnetism; and a voltage-magnetization switch device that performs magnetization reversal by voltage and the like.
Since a memory utilizing magnetism stores information based on spins of a magnetic substance, a nonvolatile memory can be implemented. Therefore such a memory is considered as one of the devices that are excellent for realizing a power-thrifty and high-speed information terminal in the future. Until now, it has been found that an artificial lattice film, made of magnetic films that are exchange-coupled via a non-magnetic film, shows a giant magnetoresistive effect (GMR) (M. N. Baibich et al., Phys. Rev. Lett., Vol. 61 (1988) 2472.), and a MRAM using a GMR film also has been proposed (K. T. M. Ranmuthu et al., IEEE Trans. on Magn. 29 (1993) 2593.). Although a non-magnetic layer in the afore-mentioned GMR film is a conductive film such as Cu, research has been conducted vigorously for a tunnel type GMR film (TMR) that uses an insulation film such as Al2O3 as the non-magnetic layer, and a MRAM using this TMR film also has been proposed. The MRAM using the TMR film is expected to realize a larger output and a higher-density memory than that using the GMR film. Along with this, the possibility of substituting for a high-density memory such as a DRAM also has started to be examined, and it has been expected to establish an architecture in several nanos to several tens of nanometers, which is intended for an ultra-high density memory in the future. For a size domain from several nanos to several tens of nanometers, in which quantal influences on the conduction become intense, a device architecture unlike a conventional one is required. Since the memory utilizing magnetism stores information on spins that are quanta, such a memory is expected as a new device and a circuit that can transmit spin information directly or that can control transmission spins directly.
Furthermore, the magnetized state in a magnetic substance is known to be determined primarily by the sum of exchange energy, crystal magnetic anisotropic energy, magnetostatic energy, and Zeeman energy generated by an external magnetic field. Among them, the physical quantities that can be controlled so as to induce magnetization reversal are the magnetostatic energy and the Zeeman energy. In the case of controlling the magnetized state of a magnetic device with electric energy, a magnetic field generated when a current flows has been used conventionally (JP 2003-92440 A).
However, for example, the energy conversion efficiency for the magnetic field generation with a line current is only about 1%. Furthermore, in the case of the line current, the intensity of a generated magnetic field is inversely proportional to a distance. In many cases, it is necessary to provide an insulator between a lead through which a line current is allowed to flow and a magnetic device that utilizes a magnetic field generated from the lead. Therefore, the energy conversion efficiency is decreased to a level less than 1%. In the case of a magnetic device whose magnetized state should be controlled with electric energy, such a thing is a factor of preventing the widespread use of it in industry.
Therefore, in order to cope with the above-stated conventional problems, it is an object of the present invention to provide a magnetic switching device and a memory using the same that can reduce substantially the energy consumption of a general magnetic device whose magnetic state is changed by an external magnetic field, which is enabled by providing a method for reversing the magnetic state in a magnetic substance at a high energy conversion efficiency and providing a preferable configuration example of a device.
A magnetic switching device of the present invention includes: at least one transition member; at least one electrode; and at least one free magnetic member. The transition member includes a perovskite compound that contains at least a rare earth element and an alkaline-earth metal. The electrode and the free magnetic member are arranged in parallel and in a noncontact manner on the transition member. At least one of the free magnetic members is coupled magnetically with the transition member. The transition member undergoes at least ferromagnetism-antiferromagnetism transition by injecting or inducing electrons or holes, whereby a magnetization direction of at least one of the free magnetic members changes.
A random access type memory of the present invention includes: a plurality of voltage switches; a plurality of transition members that undergo magnetic transition by voltages applied by the voltage switches; a plurality of free magnetic members whose magnetization directions are changed by the transition members; and a plurality of magnetoresistive effect portions that read out the magnetization directions of the free magnetic members. Each voltage switch includes a semiconductor switch device that is integrated on a semiconductor substrate. The semiconductor switch device includes at least one transition member, at least one electrode and at least one free magnetic member. The transition member includes a perovskite compound that contains at least a rare earth element and an alkaline-earth metal. The electrode and the free magnetic member are arranged in parallel and in a noncontact manner on the transition member. At least one of the free magnetic members is coupled magnetically with the transition member. The transition member undergoes at least ferromagnetism-antiferromagnetism transition by injecting or inducing electrons or holes, whereby a magnetization direction of at least one of the free magnetic members changes.
A feature of the configuration of the present invention resides in that the transition member includes a perovskite compound that contains at least a rare earth element and an alkaline-earth metal, and the electrode and the free magnetic member are arranged in parallel and in a noncontact manner on the transition member. As the rare earth element, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and the like are available, for example. As the alkaline-earth metal, Ca, Sr, Ba, Ra and the like are available, for example. As the perovskite compound, Nd0.5Sr0.5MnO3, La0.8Sr0.2CoO3, La0.2Sr0.8RuO3, La0.8Ca0.2VO3, Pr0.7Ca0.3MnO3, La0.7Ca0.3CrO3, Gd0.9Ba0.1FeO3, La0.9Sr0.1NiO3 and the like are available, for example. In the above description, the arrangement of the electrode and the free magnetic member in parallel and in a noncontact manner on the transition member means that the electrode and the free magnetic member are arranged in a noncontact manner. In other words, the electrode and the free magnetic member are arranged to be separated from each other.
Furthermore, at least one transition member, at least one electrode, at least one free magnetic member and at least one magnetization stabilization member may be included. At least one of the free magnetic members and the transition member may be coupled magnetically, and the transition member and the magnetization stabilization member may be coupled magnetically. The magnetization stabilization member may include at least one selected from the group consisting of an antiferromagnetic substance, a laminated ferrimagnetic substance and a high coercive force magnetic substance. The transition member may undergo at least ferromagnetism-antiferromagnetism transition by injecting or inducing electrons or holes, whereby a magnetization direction of the free magnetic member changes.
Furthermore, at least one transition member, at least one electrode, at least one free magnetic member, at least one magnetic member and at least one magnetization stabilization member may be included. The transition member may be arranged between the free magnetic member and the magnetic member so as to be coupled magnetically, and the magnetic member and the magnetization stabilization member may be coupled magnetically. The magnetization stabilization member may include at least one selected from the group consisting of an antiferromagnetic substance, a laminated ferrimagnetic substance and a high coercive force magnetic substance. The transition member may undergo at least ferromagnetism-antiferromagnetism transition by injecting or inducing electrons or holes, whereby a magnetization direction of the free magnetic member changes.
Furthermore, at least one transition member, at least one electrode, at least one free magnetic member, at least one magnetic member and at least one non-magnetic member may be included. The free magnetic member and the transition member may be coupled magnetically. The transition member may undergo at least ferromagnetism-antiferromagnetism transition by injecting or inducing electrons or holes, whereby a magnetization direction of the free magnetic member changes. Between the free magnetic member and the magnetic member that are connected via the non-magnetic member, a resistance may vary in accordance with a change of a magnetization relative angle.
Furthermore, at least one transition member, at least one electrode, at least one free magnetic member, at least one magnetic member, at least one non-magnetic member and at least one magnetic stabilization member may be included. At least one of the free magnetic members and the transition member may be coupled magnetically, and the transition member and the magnetization stabilization member may be coupled magnetically. The magnetization stabilization member may include at least one selected from the group consisting of an antiferromagnetic substance, a laminated ferrimagnetic substance and a high coercive force magnetic substance. The transition member may undergo at least ferromagnetism-antiferromagnetism transition by injecting or inducing electrons or holes, whereby a magnetization direction of the free magnetic member changes. Between the free magnetic member and the magnetic member that are connected via the non-magnetic member, a resistance may vary in accordance with a change of a magnetization relative angle.
Furthermore, at least one transition member, at least one electrode, at least one free magnetic member, at least two magnetic members, at least one non-magnetic member and at least one magnetic stabilization member may be included. The transition member may be arranged between the free magnetic member and one of the magnetic members so as to be coupled magnetically, and another magnetic member and the magnetization stabilization member may be coupled magnetically. The magnetization stabilization member may include at least one selected from the group consisting of an antiferromagnetic substance, a laminated ferrimagnetic substance and a high coercive force magnetic substance. The transition member may undergo at least ferromagnetism-antiferromagnetism transition by injecting or inducing electrons or holes, whereby a magnetization direction of the free magnetic member changes. Between the free magnetic member and the magnetic member that are connected via the non-magnetic member, a resistance may vary in accordance with a change of a magnetization relative angle.
Preferably, the transition member exhibits paramagnetism or non-magnetism when electrons or holes are not injected or induced.
Preferably, the transition member undergoes at least paramagnetism-ferromagnetism transition by injecting or inducing electrons or holes, and by assisting with an external magnetic field during the paramagnetism-ferromagnetism transition, a magnetization direction of the transition layer in a ferromagnetic state changes.
Preferably, the transition member further is opposed to an electrode via at least an insulation member, and by application of a voltage at least between the transition member and the electrode, the transition member undergoes magnetic transition.
In the present invention, preferably, at least one selected from the group consisting of the transition member, the magnetic member, the free magnetic member and the magnetization stabilization member includes a strongly correlated electron material. As the strongly correlated electron material, a perovskite type substance or a perovskite type analogous substance containing at least one element selected from the group consisting of group 3A, group 4A, group 5A, group 6A, group 7A, group 8, group 1B and group 2B are available.
Preferably, the strongly correlated electron material includes RE-ME-O (RE includes at least one type selected from rare-earth metal elements including Y and ME includes at least one type selected from transition metal elements).
Preferably, the strongly correlated electron material includes RE-AE-ME-O (RE includes at least one type selected from rare-earth metal elements including Y, AE includes at least one type selected from alkaline-earth metals and ME includes at least one type selected from transition metal elements).
In the present invention, a magnetic memory can be configured with a plurality of voltage switches; a plurality of transition members that undergo magnetic transition by voltages applied by the voltage switches; a plurality of free magnetic members that are arranged to be coupled magnetically with the transition members, whereby magnetization directions of the free magnetic members are changed by the transition members; and a plurality of magnetoresistive effect portions that read out the magnetization directions of the free magnetic members. Herein, a magnetic random access memory can be configured so that each voltage switch includes a semiconductor switch device that is integrated on a semiconductor substrate.
Furthermore, a reconfigurable memory also can be provided using the configurations of the magnetoresistive device and the magnetic random access memory of the present invention.
According to the present invention, at least one transition layer, at least one electrode and at least one free magnetic layer are included, and at least one of the free magnetic layers is coupled magnetically with the transition layer, and the transition layer undergoes at least magnetic phase change showing ferromagnetism by injecting or inducing electrons or holes, whereby a magnetization direction of the free magnetic layer changes. This configuration is applicable to a magnetic memory that records/reads out magnetization information of the free magnetic layer and various magnetic devices that utilize a resistance change of the magnetoresistive effect portion. Thus, this configuration can enhance the characteristics of a reproduction head of a magnetic recording apparatus used for conventional information communication terminals, such as a magneto-optical disk, a hard disk, a digital data streamer (DDS) and a digital VTR, a cylinder, a magnetic sensor for sensing a rotation speed of a vehicle, a magnetic memory (MRAM), a stress/acceleration sensor that senses a change in stress or acceleration, a thermal sensor, a chemical reaction sensor or the like.
As a material used for the transition layer (i.e., a transition member), a strongly correlated electron material preferably is used as a main component, and a perovskite type substance or a perovskite type analogous substance containing at least one element selected from the group consisting of group 3A, group 4A, group 5A, group 6A, group 7A, group 8, group 1B and group 2B preferably is used as the base material. The substances mentioned herein include Ruddlesden-Popper phase and Auriviellius phase, also.
As the strongly correlated electron material, RE-ME-O (RE includes at least one type selected from rare-earth metal elements including Y and ME includes at least one type selected from transition metal elements) particularly preferably is used. ME preferably includes, for example, at least one type selected from the group consisting of V, Cr, Mn, Fe, Co and Ni. Furthermore, RE-AE-ME-O including AE elements partially, (RE includes at least one type selected from rare-earth metal elements including Y, AE includes at least one type selected from alkaline-earth metal elements and ME includes at least one type selected from transition metal elements) preferably is used.
A preferable material that constitutes the transition layer (i.e., a material that is more preferable for the transition member) is a material that contains a crystal material represented by the general formula of RE1-xAExMEO3 as the base material. In this formula, x preferably satisfies a range of 0<x≦1. Many substances having 0 and 1 as x are semiconductor layers or insulation layers, so that it is difficult to induce magnetic phase transition by injection of carriers. On the other hand, when x is a specific value that is determined with a type of the ME element and about that value, a strongly correlated effect in which an electron system is governed by spin correlation appears remarkably, so that a phase change of the system appears.
The present invention relates to a switching device using a magnetic phase change due to strong correlation, and depending on a substance of the transition layer, the device shows antiferromagnetism without the application of an electric field and shows ferromagnetism under the application of an electric field. In addition to this, according to the present invention, a device that shows ferromagnetism without the application of an electric field and shows antiferromagnetism under the application of an electric field also can be obtained. Alternatively, a device that shows paramagnetism without the application of an electric field and shows ferromagnetism under the application of an electric field also can be obtained. By using these devices properly, the switching device can be controlled so that the magnetization direction of the free magnetic layer that is coupled magnetically with the transition layer is shifted or a coercive force is increased or decreased.
As a material used for the insulation layer, any material can be used as long as they are insulation layers and semiconductor layers. In particular, a compound of an element selected from the group consisting of: IIa to VIa including Mg, Ti, Zr, Hf, V, Nb, Ta and Cr, lanthanoid including La and Ce, IIb to IVb including Zn, B, Al, Ga and Si and an element selected from the group consisting of F, O, C, N and B, or a polyimide or a phthalocyanine based organic molecular material preferably is used.
As a material preferably used for the electrode, any material having a resistivity of 100 μΩ·cm or smaller can-be used, including Cu, Al, Ag, Au, Pt and TiN.
The magnetization stabilization layer preferably is a multilayer film of a high coercive force magnetic layer, a laminated ferrimagnetic layer and an antiferromagnetic layer or a laminated ferrimagnetic layer and an antiferromagnetic layer. As the high coercive force magnetic layer, a material having a coercive force of 1000 e or higher, including CoPt, FePt, CoCrPt, CoTaPt, FeTaPt, FeCrPt and the like, preferably is used. As the antiferromagnetic layer, PtMn, PtPdMn, FeMn, IrMn, NiMn and the like preferably are used. As the laminated ferrimagnetic layer, a multilayer structure of a magnetic layer and a non-magnetic layer preferably is used, where Co or alloys including Co, such as FeCo, CoFeNi, CoNi, CoZrTa, CoZrB and CoZrNb preferably are used as the magnetic layer and the non-magnetic layer preferably is made of Cu, Ag, Au, Ru, Rh, Ir, Re, Os or alloys and oxides of these metals.
Furthermore, a magnetic semiconductor layer preferably is used, which contains at least one type of element selected from the group consisting of I-V group, I-VI group, II-IV group, II-V group, II-VI group, III-V group, III-VI group, IV-IV group, I-III-VI group, I-V-VI group, II-III-VI group, II-IV-V group and the like, such as ZnO:Mn, ZnS:X, ZnSe:X, ZnTe:X (X=Mn, Fe, Co, Ni), MnAs, JTiO3:Mn (J=Mg, Ca, Sr, Ba), XF2, ZnF2:X (X=Mn, Fe, Co, Ni), CdTe:Mn, CdSe:X, and contains at least one element selected from the group consisting of IVa to VIII and Ib in the compound semiconductor layer so that its magnetism is induced.
Furthermore, as the magnetic layer constituting the free magnetic layer, ferromagnetic layers including a TMA (T denotes at least one type selected from the group consisting of Fe, Co and Ni, M denotes at least one type selected from the group consisting of Mg, Ca, Ti, Zr, Hf, V, Nb, Ta, Cr, Al, Si, Mg, Ge and Ga, and A denotes at least one type selected from the group consisting of N, B, O, F and C) typified by Fe, Co, Ni, FeCo alloy, NiFe alloy, CoNi alloy, NiFeCo alloy, nitrides, oxides, carbides, borides and fluorides magnetic layers such as FeN, FeTiN, FeAlN, FeSiN, FeTaN, FeCoN, FeCoTiN, FeCo(Al,Si)N and FeCoTaN and a TL (T denotes at least one type selected from the group consisting of Fe, Co and Ni, and L denotes at least one type selected from the group consisting of Cu, Ag, Au, Pd, Pt, Rh, Ir, Ru, Os, Ru, Si, Ge, Al, Ga, Cr, Mo, W, V, Nb, Ta, Ti, Zr, Hf, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) typified by FeCr, FeSiAl, FeSi, FeAl, FeCoSi, FeCoAl, FeCoSiAl, FeCoTi, Fe(Ni)(Co)Pt, Fe(Ni)(Co)Pd, Fe(Ni)(Co)Rh, Fe(Ni)(Co)Ir, Fe(Ni)(Co)Ru, FePt and the like; a half metal material typified by LaSrMnO, LaCaSrMnO and CrO2; magnetic semiconductor layers typified by QDA (Q denotes at least one type selected from the group consisting of Sc, Y, lanthanoid, Ti, Zr, Hf, Nb, Ta and Zn, A denotes at least one type selected from the group consisting of C, N, O, F, and S, and D denotes at least one type selected from the group consisting of V, Cr, Mn, Fe, Co and Ni) and RDA (R denotes at least one type selected from the group consisting of B, Al, Ga and In, D denotes at least one type selected from the group consisting of V, Cr, Mn, Fe, Co and Ni, and A denotes at least one type selected from the group consisting of As, C, N, O, P and S); a perovskite oxide; a spinel type oxide such as ferrite; and a garnet type oxide are preferably used.
Explanations are given below, with reference to the drawings.
It is preferable that, as shown in
Furthermore, as shown in
Next, as shown in
As shown in
A switching operation using such an in-plane arrangement can be implemented by the characteristics of the magnetic phase change possessed by the transition layer that is capable of spreading to all layers. Conceivably, this results from a distinctive filling control caused by the use of a strongly correlated electron material as the transition layer. From this, although FIGS. 1 to 5 show typical cross-sectional configurations, a desired device can be realized even with in-plane arrangements as in
As shown in
As shown in
The afore-mentioned configurations of the present invention can be implemented by conventional thin-film processes and micromachining processes. The respective magnetic layers, the antiferromagnetic layers, the interlayer insulation layers and the electrodes and the like can be manufactured by PVD methods including sputtering methods such as pulse laser deposition (PLD), ion beam deposition (IBD), cluster ion beam deposition, RF, DC, ECR, helicon, ICP and an opposed target, MBE, ion plating, or the like, as well as other CVD methods, a plating method, a sol-gel method or the like.
As micromachining, a physical or chemical etching method generally used for a semiconductor process, a GMR head production process and the like, such as ion milling, RIE and FIB may be combined with a photolithography technique using a stepper and an EB method for forming a fine pattern. Furthermore, for planarization of the surface of the electrodes and the like, CMP and cluster-ion beam etching also are used effectively.
The use of magnetic switching devices having the thus described configurations enables the production of a magnetic memory.
On the other hand, during reading, a field effect transistor (FET) 42 is turned ON as shown in
Note here that although
The following describes more specific working examples.
Samples were manufactured in the following manner using a pulse laser deposition (PLD) technique and a magnetron sputter method:
Sample 1-1
A laminated body was manufactured so that MgO(100) substrate/NdBa2Cu3O7(300)/Nd0.5Sr0.5MnO3(100)/Ni0.81Fe0.19(20)/Cu(3)/Co0.9Fe0.1(20) were laminated in this stated order (the unit of numerals in parentheses is nm, which show thicknesses).
The NdBa2Cu3O7 layer and the Nd0.5Sr0.5MnO3 layer were manufactured by PLD at a substrate temperature of about 600 to 800° C. (typically 750° C.), and each layer of NiFe, Cu and CoFe was manufactured by sputtering at a substrate temperature of a room temperature (27° C.).
During the PLD and the sputtering, the sample was conveyed so as to maintain high vacuum (in-situ transportation).
Processing was conducted on the laminated body by an electron beam (EB) technique and a photolithography technique so as to manufacture the configuration as shown in
The configuration was manufactured by the process shown in
As electrodes for wiring, Au, Ag, Pt, Cu, Al and the like were used. In this working example, an electrode having a multilayer structure such as Ta(5)/Cu(500)/Pt(10) was used with consideration given to a contacting property and the resistance to processing.
Herein, the NdBa2Cu3O7 layer was a conductive oxide and was provided as the electrode, and the Nd0.5Sr0.5MnO3 layer was provided as the transition layer and the NiFe layer, the Cu layer and the CoFe layer were provided as the free magnetic layer, the non-magnetic layer and the fixed magnetic layer, respectively. Herein, the magnetic multilayer film of Ni0.81Fe0.19/Cu/Co0.9Fe0.1 formed a magnetoresistive changing part having a configuration of a CPP type GMR.
The operation of the magnetic switching device configured in this working example was confirmed as follows:
Firstly, as shown in
From the afore-mentioned magnetic resistance characteristics using the B-S terminals, it was shown that the magnetoresistive effect could be detected naturally by the application of an external magnetic field also, and the device of the present invention was a magnetoresistive changing type switching device.
From this, the basic operation of the switching device having magnetic properties capable of magnetization reversal without the use of an external magnetic field could be confirmed.
Conceivably, in order to obtain such desired characteristics of the present invention, it is important to have a favorable crystallographic consistency between the electrode and the transition layer. Since a perovskite type (including analogous substances) oxide was used for both, the desired characteristics were realized by a favorable compatibility between them.
In the configuration shown in
In addition to Sample 1-1, Sample 1-2 was manufactured including MgO(100)substrate/NdBa2Cu3O7(300)/Nd0.6Sr0.4MnO3(50)/Nd0.5Sr0.5MnO3(50)/Ni0.81Fe0.19(20)/Cu(3)/Co0.9Fe0.1(5)/Ru(0.9)/Co0.9Fe0.1(5)/IrMn(15)(the unit of numerals in parentheses is nm, which show thicknesses), which were substrate/electrode/antiferromagnetic layer/transition layer/free magnetic layer/non-magnetic layer/fixed magnetic layer. The sample was annealed in the magnetic field at 5 kOe and 280° C. for the alignment of magnetization direction of IrMn. Herein, Co0.9Fe0.1(5)/Ru(0.9)/Co0.9Fe0.1(5)/IrMn(15) formed a fixed magnetic layer having a synthetic ferri type antiferromagnetism coupling structure.
The evaluations similar to Sample 1-1 were conducted to Sample 1-2 also, and an operation as a magnetic switching device was confirmed also in this configuration.
Furthermore, Sample 1-3 was manufactured including MgO(100) substrate/NdBa2Cu3O7(300)/Nd0.6Sr0.4MnO3(50)/Nd0.4Sr0.6MnO3(50)/Nd0.5Sr0.5MnO3(50)/Ni0.81Fe0.19(20)/Co0.5Fe0.5(1)/Al2O3(1.2)/Co0.5Fe0.5(5)/Ru(0.9)/Co0.5Fe0.5(5)/IrMn(15) (the unit of numerals in parentheses is nm, which show thicknesses), which were substrate/electrode/antiferromagnetic layer/ferromagnetic layer/transition layer/free magnetic layer/non-magnetic layer/fixed magnetic layer. The sample was annealed in the magnetic field at 5 kOe and 280° C. for the alignment of magnetization direction of IrMn.
Herein, Ni0.81Fe0.19(20)/Co0.5Fe0.5(1) was the free magnetic layer and Co0.5Fe0.5(5)/Ru(0.9)/Co0.5Fe0.5(5)/IrMn(15) formed the fixed magnetic layer. The Al2O3 layer was the insulative non-magnetic layer, and Ni0.81Fe19/Co0.5Fe0.5/Al2O3/Co0.5Fe0.5/Ru/Co0.5Fe0.5/IrMn constituted a tunnel type magnetoresistive changing portion.
Al2O3 as the non-magnetic insulation layer was manufactured by forming an Al film, which was subjected to oxidation, followed by post-oxidation process and was manufactured by sputtering of Al2O3. In the post-oxidation process, oxidation was conducted by natural oxidation in a vacuum chamber, by natural oxidation by the application of heat in a vacuum chamber, and by oxidation in plasma in a vacuum chamber. Any process of these could realize a favorable non-magnetic insulation film that functioned as a tunnel barrier. Note here that multi-stages of Al film formation, natural oxidation, Al film formation and natural oxidation may be conducted during the post-oxidation process, and it was found that such a process improved the uniformity of the oxidation film, as well as enabling the reduction of a oxidation time.
The evaluations similar to Sample 1-1 were conducted. A change in resistance was 30% or higher before and after the application of a voltage to the transition layer, and an operation as a magnetic switching device was confirmed in this configuration also.
In this working example, NdBa2Cu3O7 was used as the electrode, which was a conductive oxide layer. In addition to this, REBa2Cu3O7 (Y, La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb were used as RE) could be used, which showed a favorable compatibility with the transition layer and the substrate.
Furthermore, in this working example, MgO was used as the substrate. However, other oxide substrates such as LaAlO3, NdGaO3, SrTiO3, LaSrAlTaO4 and the like could be used and the device could be embodied. The use of such a substrate allows strongly correlated electron materials constituting the transition layer, the electrode, the antiferromagnetic layer and the ferromagnetic layer to be produced as monocrystals, and therefore is preferable.
Herein, a configuration in which Si/SiO2 (thermal oxidation) is used as the substrate and Si/SiO2/Pt(electrode)/(Nd, Sr)MnO3(transition layer)/NiFe(free magnetic layer)/Al2O3 (non-magnetic layer)/(CoFe/IrMn)(fixed magnetic layer) is included also enables the embodiment of the device, although the transition layer is a polycrystal layer, and the magnetic switching operation of the present invention can be realized.
In addition to this, a desired device can be realized also by adopting a perovskite oxide (RE, Sr, Ca)MnO3 (Y, La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb were used as RE) as the transition layer.
Samples were manufactured in the following manner using a pulse laser deposition (PLD) technique and a magnetron sputter method:
A laminated body was manufactured as Sample 2-1 so as to include SrTiO3(100)substrate/NdBa2Cu3O7(300)/SrTiO3(50)/Nd0.6Sr0.4MnO3(50)/Nd0.4Sr0.6MnO3(50)/Nd0.5Sr0.5MnO3(50)/Ni0.81Fe0.19(20)/Co0.5Fe0.5(1)/Al2O3(1.2)/Co0.5Fe0.5(5)/Ru(0.9)/Co0.5Fe0.5(5)/IrMn(15) that were laminated in this stated order (the unit of numerals in parentheses is nm, which show thicknesses).
The NdBaCuO layer and the respective NdSrMnO layers were manufactured by PLD at a substrate temperature of about 600 to 800° C., and each layer of NiFe, Cu, CoFe, Ru and IrMn was manufactured by sputtering at a substrate temperature of a room temperature (27° C.).
During the PLD and the sputtering, the sample was conveyed so as to maintain high vacuum (in-situ transportation).
Processing was conducted on the laminated body by an electron beam (EB) technique and a photolithography technique, which were in conformance with
Al2O3 as the non-magnetic insulation layer was manufactured by forming an Al film, which was subjected to oxidation, followed by post-oxidation processing. During this step, multi-stages of A (0.4 nm) film formation, natural oxidation, Al (0.3 nm) film formation, natural oxidation, Al (0.3 nm) film formation and natural oxidation was conducted. Al2O3 after the oxidation had a film thickness of 1.5 nm.
The operation of the magnetic switching device configured in this working example was confirmed as follows:
Firstly, as shown in
In this connection, it can be considered that the charge injection from the electrode to the transition layer via the insulation layer caused magnetic phase transition of the transition layer. Since the magnetic resistance change could be obtained with a sufficient gain, it was found that the configuration via the insulation layer of this working example was favorable.
From the afore-mentioned magnetic resistance characteristics using the B-S terminals, it was shown that the magnetoresistive effect could be detected naturally by the application of an external magnetic field also, and the device of the present invention was a magnetoresistive changing type switching device.
From this, the basic operation of the switching device having magnetic properties capable of magnetization reversal without the use of an external magnetic field could be confirmed.
In addition to Sample 2-1, Sample 2-2 was manufactured including NdGaO3(100)substrate/La0.7Sr0.3MnO3(200)/SrTiO3(50)/Nd0.6Sr0.4MnO3(50)/Sm00.5MnO3(50)/Ni0.81Fe0.19(20)/Co0.5Fe0.5(1)/Al2O3(1.2)/Co0.5Fe0.5(5)/Ru(0.9)/Co0.5Fe0.5(5)/PtMn(15) (the unit of numerals in parentheses is nm, which show thicknesses), which were substrate/electrode/insulation layer/antiferromagnetic layer/transition layer/free magnetic layer/non-magnetic layer/fixed magnetic layer. The sample was annealed in the magnetic field at 5 kOe and 280° C. for the alignment of magnetization direction of PtMn. Herein, Co0.9Fe0.1(5)/Ru(0.9)/Co0.9Fe0.1(5)/PtMn(15) formed a fixed magnetic layer having a synthetic ferri type antiferromagnetism coupling structure.
The evaluations similar to Sample 2-1 were conducted to Sample 2-2 also, and an operation as a magnetic switching device was confirmed also in this configuration.
Furthermore, Sample 2-3 was manufactured including LaSrAlTaO4(100)substrate/La0.7Sr0.3MnO3(200)/SrTiO3(50)/Nd0.6Sr0.4MnO3(50)/Sm0.5Sr0.5MnO3(50)/Ni0.81Fe0.19(20)/Co0.5Fe0.5(1)/Al2O3(1.2)/Co0.5Fe0.5(5)/Ru(0.9)/Co0.5Fe0.5(5)/IrMn(15/) (the unit of numerals in parentheses is nm, which show thicknesses), which were substrate/electrode/antiferromagnetic layer/ferromagnetic layer/transition layer/free magnetic layer/non-magnetic layer/fixed magnetic layer. The sample was annealed in the magnetic field at 5 kOe and 280° C. for the alignment of magnetization direction of IrMn.
Herein, Ni0.81Fe0.19(20)/Co0.5Fe0.5(1) was the free magnetic layer and Co0.5Fe0.5(5)/Ru(0.9)/Co0.5Fe0.5(5)/IrMn(15) formed the fixed magnetic layer. The Al2O3 layer was the insulative non-magnetic layer, and Ni0.81Fe0.19/Co0.5Fe0.5/Al2O3/Co0.5Fe0.5/Ru/Co0.5Fe0.5/IrMn constituted a tunnel type magnetoresistive changing portion.
In Sample 2-2 and Sample 2-3, La0.7Sr0.3MnO3 was used as the electrode, which was a conductive oxide layer. In addition to this, (Sr1-xCax)1-yLayRuO3 (where 0≦x≦1, 0≦y≦0.9) and Sr1-xLaxTi1-yMEyO3 (where 0≦x≦0.9, 0≦y≦1, ME=V, Nb, Ta, Cr, Mn, Fe, Co, Ni, Cu, Re or Ru) could be used, which showed a favorable compatibility with the transition layer and the substrate.
Furthermore, in this working example, MgO was used as the substrate. However, other oxide substrates such as LaAlO3, NdGaO3, SrTiO3, (La, Sr)2(Al, Ta)O3 and the like could be used and the device could be embodied. The use of such a substrate allows strongly correlated electron materials constituting the transition layer, the electrode, the antiferromagnetic layer and the ferromagnetic layer to be produced as monocrystals, and therefore is preferable.
Herein, a configuration in which Si/SiO2 (thermal oxidation) is used as the substrate and Si/SiO2/Pt (electrode)/(Nd, Sr)MnO3(transition layer)/NiFe(free magnetic layer)/Al2O3(non-magnetic layer)/(CoFe/IrMn) (fixed magnetic layer) is included also enables the embodiment of the device, although the transition layer is a polycrystal layer, and the magnetic switching operation of the present invention can be realized.
Furthermore, another configuration in which a Si substrate is used and Si substrate/TiN (underlayer)/Pt (electrode)/(Nd, Sr)MnO3 (transition layer)/NiFe (free magnetic layer)/Al3O3(non-magnetic layer)/(CoFe/IrMn) (fixed magnetic layer) is included also can realize the magnetic switching operation of the present invention.
Moreover, still another configuration in which MgO(100) is used as a substrate and MgO substrate/Pt (electrode)/(Nd, Sr)MnO3(transition layer)/NiFe (free magnetic layer)/Al2O3(non-magnetic layer)/(CoFe/IrMn) (fixed magnetic layer) is included also can realize the magnetic switching operation of the present invention, although the transition layer is a polycrystal layer.
In addition to this, a desired device can be realized also by adopting a perovskite oxide (RE, Sr, Ca)MnO3 (Y, La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb were used as RE) as the transition layer.
Samples were manufactured in the following manner using a magnetron sputter method:
A laminated body was manufactured as Sample 3-1 so as to include MgO(100)substrate/Pt(500) SrTiO3(50)/Nd0.6Sr0.4MnO3(50)/Nd0.4Sr0.6MnO3(50)/Nd0.5Sr0.5MnO3(50)/La0.7Sr0.3MnO3(1.2)/Ni0.81Fe0.19(20)/Co0.5Fe0.5(1)/Al2O3(1.5)/Co0.5Fe0.5(9)/Ru(0.9)/Co0.5Fe0.5(9)/IrMn(15) that were laminated in this stated order (the unit of numerals in parentheses is nm, which show thicknesses).
Each layer of the SrTiO3 layer, the NdSrMnO3 layer and the LaSrMnO3 layer was manufactured at a substrate temperature of about 600 to 850° C., and each layer of Pt, NiFe, Cu, CoFe, Ru and IrMn was manufactured by sputtering at a substrate temperature of a room temperature (27° C.). Herein, Pt as a lower electrode was heated by a high-temperature film formation step that was conducted downstream. The film formation was conducted in an in-situ manner.
Processing was conducted to the laminated body by an electron beam (EB) technique and a photolithography technique, which were in conformance with FIGS. 20A-I, to manufacture the configuration as shown in
Herein, the magnetic multilayer film of Ni0.81Fe0.19(20)/Co0.5Fe0.5(1)/Al2O3(1.5)/Co0.5Fe0.5(9)/Ru(0.9)/Co0.5Fe0.5(9)/IrMn(15) formed a magnetoresistive changing part having a TMR type configuration.
Al2O3 as the non-magnetic insulation layer was manufactured by forming an Al film, which was subjected to oxidation, followed by post-oxidation process. During this step, multi-stages of Al (0.4 nm) film formation, natural oxidation, Al (0.3 nm) film formation, natural oxidation, Al (0.3 nm) film formation and natural oxidation was conducted. Al2O3 after the oxidation had a film thickness of 1.5 nm.
The operation of the magnetic switching device configured in this working example was confirmed as follows:
Firstly, as shown in
In this connection, it can be considered that the charge injection from the electrode to the transition layer via the insulation layer caused magnetic phase transition of the transition layer. Since the magnetic resistance change could be obtained with a sufficient gain, it was found that the configuration via the insulation layer of this working example was favorable.
From the afore-mentioned magnetic resistance characteristics using the B-S terminals, it was shown that the magnetoresistive effect could be detected naturally by the application of an external magnetic field also, and the device of the present invention was a magnetoresistive changing type switching device.
From this, the basic operation of the switching device having magnetic properties capable of magnetization reversal without the use of an external magnetic field could be confirmed.
Next, a laminated body was manufactured as Sample 3-2 so as to include NdGaO3(100)substrate/La0.7Sr0.3MnO3(100)/LaAlO3(1.5)/SrTiO3(50)/LaAlO3(1.5)/Nd0.6Sr0.4MnO3(30)/Nd0.4Sr0.6MnO3(25)/PrBaMn2O6(50)/La0.7Ba0.3MnO3(1.2)/Ni0.81Fe0.19(20)/Co0.5Fe0.5(1)/Al2O3(1.5)/Co0.5Fe0.5(9)/Ru(0.9)/Co0.5Fe0.5(9)/IrMn(15) that were laminated in this stated order (the unit of numerals in parentheses is nm, which show thicknesses).
The SrTiO3 layer and the LaAlO3 layer and the respective layers of the NdSrMnO layer, the LaSrMnO layer, the PrBaMnO layer and the LaBaMnO layer were manufactured at a substrate temperature of about 600 to 850° C., and each layer of Pt, NiFe, Cu, CoFe, Ru and IrMn was manufactured by sputtering at a substrate temperature of a room temperature (27° C.). The film formation and the conveyance between the respective film formation steps were conducted in an in-situ manner.
Processing was conducted to the laminated body by an electron beam (EB) technique and a photolithography technique, which were in conformance with FIGS. 20A-I, to manufacture the configuration in conformance with
Herein, the magnetic multilayer film of Ni0.81Fe0.19(20)/Co0.5Fe0.5(1)/Al2O3(1.5)/Co0.5Fe0.5(9)/Ru(0.9)/Co0.5Fe0.5(9)/IrMn(15) formed a magnetoresistive changing part having a TMR type configuration.
Al2O3 as the non-magnetic insulation layer was manufactured by forming an Al film, which was subjected to oxidation, followed by post-oxidation processing. During this step, multi-stages of Al (0.4 nm) film formation, natural oxidation, Al (0.3 nm) film formation, natural oxidation, Al (0.3 nm) film formation and natural oxidation was conducted. Al2O3 after the oxidation had a film thickness of 1.5 nm.
When a voltage 0.1 V≦V≦20 V was applied between the S-W terminals, about 30% of difference in resistance could be detected between the B-S terminals, which showed the formation of a desired device.
Samples were manufactured in the following manner using a pulse laser deposition (PLD) technique and a magnetron sputter method:
A laminated body was manufactured as Sample 4-1, where a NdGaO3(100) substrate was used and NdGaO3substrate/Nd0.5Sr0.5MnO3(100)/La0.7Sr0.3MnO3 (1.5) were laminated in this stated order (the unit of numerals in parentheses is nm, which show thicknesses).
The Nd0.5Sr0.5MnO3 layer and the La0.7Sr0.3MnO3 layer were manufactured by PLD at a substrate temperature of about 750 to 900° C.
Processing was conducted to the laminated body by an electron beam (EB) technique and a photolithography technique and a device was manufactured by the procedure as shown in
Thereafter, the transition layer 43 was processed in
In
As electrodes for wiring, Au, Ag, Pt, Cu, Al and the like were used. In this working example, an electrode having a multilayer structure such as Ta(5)/Cu(500)/Pt(10) was used with consideration given to a contacting property and the resistance to processing. In this step, reverse-sputtering was conducted before the deposition for the purpose of surface-etching of the La0.7Sr0.3MnO3(10) layer.
Herein, the Nd0.5Sr0.5MnO3 layer was provided as the transition layer, the La0.7Sr0.3MnO3(10 reverse-sputtered)/Ni0.81Fe0.19(20)/Co0.5Fe0.5(1) layer was provided as the free magnetic layer, the Al2O3 layer was provided as the non-magnetic layer and the Co0.5Fe0.5(5)/Ru(0.9)/Co0.5Fe0.5(5)/IrMn(15) layer was provided as the fixed magnetic layer.
Al2O3 as the non-magnetic insulation layer was manufactured by forming an Al film, which was then subjected to multi-stage oxidation processing.
The thus manufactured device typically had a configuration of
The operation of the magnetic switching device configured in this working example was confirmed as follows:
Firstly, as shown in
From the afore-mentioned magnetic resistance characteristics using the B-S terminals, it was shown that the magnetoresistive effect could be detected naturally by the application of an external magnetic field also, and the device of the present invention was a magnetoresistive changing type switching device.
From this, the basic operation of the switching device having magnetic properties capable of magnetization reversal without the use of an external magnetic field could be confirmed.
In addition to Sample 4-1, a laminated body was manufactured as Sample 4-2 including NdGaO3 substrate/PrBaMn2O6(100)/La0.7Sr0.3MnO3(1.5) (the unit of numerals in parentheses is nm, which show thicknesses).
The PrBaMn2O6 layer and the La0.7Sr0.3MnO3 layer were formed by PLD at a substrate temperature of about 750 to 900° C.
Processing was conducted on the laminated body by an electron beam (EB) technique and a photolithography technique and a device was manufactured by the process as shown in
The transition layer was processed in
In
As electrodes for wiring, Au, Ag, Pt, Cu, Al and the like were used. In this working example, an electrode having a multilayer structure such as Ta(5)/Cu(500)/Pt(10) was used with consideration given to a contacting property and the resistance to processing. In this step, reverse-sputtering was conducted before the deposition for the purpose of surface-etching of the La0.7Sr0.3MnO3 (10) layer.
Herein, the PrBaMn2O6 layer was the transition layer having an A-site ordered perovskite structure, and the La0.7Sr0.3MnO3 (1.5-reverse-sputtered)/Ni0.81Fe0.19(20)/Co0.5Fe0.5(1) layer was provided as the free magnetic layer, the Al2O3 layer was provided as the non-magnetic layer and the Co0.5Fe0.5(9)/Ru(0.9)/Co0.5Fe0.5(9)/IrMn(15) layer was provided as the fixed magnetic layer.
Al2O3 as the non-magnetic insulation layer was manufactured by forming an Al film, which was then subjected to multi-stage oxidation processing.
When a voltage 0.1 V≦V≦20 V was applied between W1-W2 terminals, about 40% of difference in resistance could be detected between B-S terminals at a room temperature, which showed the formation of a desired device.
From the afore-mentioned magnetic resistance characteristics using the B-S terminals, it was shown that the magnetoresistive effect could be detected naturally by the application of an external magnetic field also, and the device of the present invention was a magnetoresistive changing type switching device.
From this, the basic operation of the switching device having magnetic properties capable of magnetization reversal without the use of an external magnetic field could be confirmed.
Although PrBaMn2O6 was used as the transition layer in this example, when a substance represented by RE1AE1ME2O6 (RE is a rare earth element, e.g., La, Sm and Gd; AE is an alkaline-earth metal element, e.g., Ba; ME is a transition metal element, e.g., Mn and Co) was used, similar results could be obtained.
Furthermore, in this working example, MgO was used as the substrate. However, other oxide substrates such as LaAlO3, NdGaO3, SrTiO3, LaSrAlTaO4 and the like could be used and the device could be embodied. The use of such a substrate allows strongly correlated electron materials constituting the transition layer, the electrode, the antiferromagnetic layer and the ferromagnetic layer to be produced as monocrystals, and therefore is preferable.
Furthermore, a configuration in which Si/SiO2 (thermal oxidation) is used as the substrate and Si/SiO2/Pt (electrode)/(Nd, Sr)MnO3 (transition layer)/NiFe (free magnetic layer)/Al2O3 (non-magnetic layer)/(CoFe/IrMn) (fixed magnetic layer) is included also enables the embodiment of the device, although the transition layer is a polycrystal layer, and the magnetic switching operation of the present invention as shown in
Next, a configuration of
The PrBaMn2O6 layer and the La0.7Sr0.3MnO3 layer were formed by PLD at a substrate temperature of about 750 to 900° C.
The other layers were deposited by sputtering at a room temperature (27° C.). Processing was conducted to the laminated body by EB (electron beam) processing and a photolithography technique, so as to form a device.
The operation of the magnetic switching device configured in this working example was confirmed as follows: firstly, a resistance between B-S terminals was measured beforehand. Next, a voltage was applied between W1-W2 terminals, and after the W1-W2 terminals were disconnected, the resistance between the B-S terminals was measured again, whereby the operation of the switching device of the present invention was evaluated. When a voltage 0.1 V≦V≦20 V was applied between the electrode and the free magnetic layer, about 20% of difference in resistance could be detected between the B-S terminals at a room temperature, which showed the formation of a desired device.
From the afore-mentioned magnetic resistance characteristics using the B-S terminals, it was shown that the magnetoresistive effect could be detected naturally by the application of an external magnetic field also, and the device of the present invention was a magnetoresistive changing type switching device.
From this, the basic operation of the switching device having magnetic properties capable of magnetization reversal without the use of an external magnetic field could be confirmed.
Although the magnetoresistive changing portion in this example had a TMR device structure, in the case of a GMR structure, the operation of the device could be confirmed with the configuration of
In addition to this, a desired device can be realized also by adopting a perovskite oxide (RE, Sr, Ca)MnO3 (Y, La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb were used as RE) as the transition layer.
Samples were manufactured in the following manner using a pulse laser deposition (PLD) technique and a magnetron sputter method.
The following laminated bodies of Sample 5-1 to 5-7 were formed. The unit of numerals in parentheses is nm, which show thicknesses.
Sample 5-1:
NdGaO3(100) substrate/La0.7Sr0.3MnO3(80)/LaAlO3(1.5)/SrTiO3(50)/LaAlO3(1.5)/Nd0.6Sr0.4MnO3(30)/Nd0.4Sr0.6MnO3(25)/La0.8Sr0.2CoO3(50)/La0.7Sr0.3MnO3(1.2)/Ni0.81Fe0.19(20)/Co0.5Fe0.5(1)/Al2O3(1.5)/Co0.5Fe0.5(9)/Ru(0.9)/Co0.5Fe0.5(9)/IrMn(15)
Sample 5-2:
NdGaO3(100) substrate/La0.7Sr0.3MnO3(80)/LaAlO3(1.5)/SrTiO3(50)/LaAlO3(1.5)/Nd0.6Sr0.4MnO3(30)/Nd0.4Sr0.6MnO3(25)/La0.2Sr0.8RuO3(50)/La0.7Sr0.3MnO3(1.2)/Ni0.81Fe0.19(20)/Co0.5Fe0.5(1)/Al2O3(1.5)/Co0.5Fe0.5(9)/Ru(0.9)/Co0.5Fe0.5(9)/IrMn(15)
Sample 5-3:
SrTiO3(100) substrate/La0.7Sr0.3MnO3(80)/LaAlO3(1.5)/SrTiO3(50)/LaAlO3(1.5)/Nd0.6Sr0.4MnO3(30)/Nd0.4Sr0.6MnO3(25)/La0.8Ca0.2VO3(50)/La0.7Sr0.3MnO3(1.2)/Ni0.81Fe0.19(20)/Co0.5Fe0.5(1)/Al2O3(1.5)/Co0.5Fe0.5(9)/Ru(0.9)/Co0.5Fe0.5(9)/IrMn(15)
Sample 5-4:
SrTiO3(100) substrate/La0.7Sr0.3MnO3(80)/LaAlO3(1.5)/SrTiO3(50)/LaAlO3(1.5)/Nd0.6Sr0.4MnO3(30)/Nd0.4Sr0.6MnO3(25)/Pr0.7Ca0.3MnO3(50)/La0.7Sr0.3MnO3(1.2)/Ni0.81Fe0.19(20)/Co0.5Fe0.5(1)/Al2O3(1.5)/Co0.5Fe0.5(9)/Ru(0.9)/Co0.5Fe0.5(9)/IrMn(15)
Sample 5-5:
SrTiO3(100) substrate/La0.7Sr0.3MnO3(80)/LaAlO3(1.5)/SrTiO3(50)/LaAlO3(1.5)/Nd0.6Sr0.4nO3(30)/Nd0.4Sr0.6MnO3(25)/La0.7Ca0.3CrO3(50)/La0.7Sr0.3MnO3(1.2)/Ni0.81Fe0.19(20)/Co0.5Fe0.5(1)/Al2O3(1.5)/Co0.5Fe0.5(9)/Ru(0.9)/Co0.5Fe0.5(9)/IrMn(15)
Sample 5-6:
SrTiO3(100) substrate/La0.7Sr0.3MnO3(80)/LaAlO3(1.5)/SrTiO3(50)/LaAlO3(1.5)/Nd0.6Sr0.4MnO3(30)/Nd0.4Sr0.6MnO3(25)/Gd0.9Ba0.1FeO3(50)/La0.7Sr0.3MnO3(1.2)/Ni0.81Fe0.19(20)/Co0.5Fe0.5(1)/Al2O3(1.5)/Co0.5Fe0.5(9)/Ru(0.9)/Co0.5Fe0.5(9)/IrMn(15)
Sample 5-7:
SrTiO3(100) substrate/La0.7Sr0.3MnO3(80)/LaAlO3(1.5)/SrTiO3(50)/LaAlO3(1.5)/Nd0.6Sr0.4MnO3(30)/Nd0.4Sr0.6MnO3(25)/La0.9Sr0.1NiO3(50)/La0.7Sr0.3MnO3(1.2)/Ni0.81Fe0.19(20)/Co0.5Fe0.5(1)/Al2O3(1.5)/Co0.5Fe0.5(9)/Ru(0.9)/Co0.5Fe0.5(9)/IrMn(15)
Each layer was formed by a PLD method at a substrate temperature of about 600 to 850° C., and each layer of NiFe, Cu, CoFe, Ru and IrMn was manufactured by sputtering at a substrate temperature of a room temperature. The film formation and the conveyance between the respective film formation steps were conducted in an in-situ manner.
Processing was conducted on the laminated bodies by an electron beam (EB) technique and a photolithography technique, which were in conformance with FIGS. 20A-I, to manufacture the configuration in conformance with
Herein, the magnetic multilayer film of Ni0.81Fe0.19(20)/Co0.5Fe0.5(1)/Al2O3(1.2)/Co0.5Fe0.5(5)/Ru(0.9)/Co0.5Fe0.5(5)/IrMn(15) formed a magnetoresistive changing part having a TMR type configuration.
As the transition layer, Sample 5-1 used the La0.8Sr0.2CoO3 layer, Sample 5-2 used the La0.2Sr0.8RuO3 layer, Sample 5-3 used the La0.8Ca0.2VO3 layer, Sample 5-4 used the Pr0.7Ca0.3MnO3 layer, Sample 5-5 used the La0.7Ca0.3CrO3 layer, Sample 5-6 used the Gd0.9Ba0.1FeO3 layer, and Sample 5-7 used the La0.9Sr0.1NiO3 layer.
Al2O3 as the non-magnetic insulation layer was manufactured by forming an Al film, which was subjected to oxidation, followed by post-oxidation process. During this step, multi-stages of Al (0.4 nm) film formation, natural oxidation, Al (0.3 nm) film formation, natural oxidation, Al (0.3 nm) film formation and natural oxidation was conducted. Al2O3 after the oxidation had a film thickness of 1.5 nm.
When a voltage 0.1 V≦V≦20 V was applied between the S-W terminals, about at least 20% of difference in resistance could be detected between the B-S terminals of all samples, which showed the formation of desired devices.
Samples were manufactured in the following manner using a pulse laser deposition (PLD) technique and a magnetron sputter method.
Sample 6-1
A laminated body was manufactured so as to include NdGaO3(100) substrate/La0.7Sr0.3MnO3(80)/LaAlO3(1.5)/SrTiO3(50)/LaAlO3(1.5)/Gd0.7Ca0.3BaMn2O6(150)/Ni0.81Fe0.19(20)/Co0.5Fe0.5(1)/Al2O3(1.5)/Co0.5Fe0.5(9)/Ru(0.9)/Co0.5Fe0.5(9)/IrMn(15) (the unit of numerals in parentheses is nm, which show thicknesses), which was a configuration in conformance with
The Gd0.7Ca0.3BaMn2O3 layer constituting a transition layer exhibits paramagnetism at a room temperature.
When a voltage was applied between a S terminal and a W terminal, while a pulse current (maximum 10 mA, 1 μs) was applied using an electrode wiring, an external magnetic field was generated effectively so as to enable the operation.
As compared with the case where the pulse current is not applied, the applied voltage could be reduced by about 25%. From this, effective driving could be carried out in terms of a low power consumption operation. Furthermore, since paramagnetism appeared without the application of a voltage, the coupling state of the magnetic layers could be controlled, and a portion of a free magnetic layer could be made independent, which showed that the configuration was suitable for the memory operation.
Samples were manufactured in the following manner using a pulse laser deposition (PLD) technique and a magnetron sputter method.
Sample 6-1
A device configuration was formed in conformance with FIGS. 20A-I, including SrTiO3(100) substrate/SrRuO3(100)/La0.7Sr0.3MnO3(80)/Gd0.7Ca0.3BaMn2O6(100) /La0.7Sr0.3MnO3(1.2)/Ni0.81Fe0.19(20)/Co0.5Fe0.5(1)/Al2O3(1.5)/Co0.5Fe0.5(9)/Ru(0.9)/Co0.5Fe0.5(9)/IrMn(15) (the unit of numerals in parentheses is nm, which show thicknesses).
Each layer was formed by a PLD method at a substrate temperature of about 600 to 850° C., and each layer of NiFe, Cu, CoFe, Ru and IrMn was manufactured by sputtering at a substrate temperature of a room temperature (27° C.). The film formation and the conveyance between the respective film formation steps were conducted in an in-situ manner.
Processing was conducted on the laminated body by an electron beam (EB) technique and a photolithography technique, which were in conformance with FIGS. 20A-I. Herein, the SrRuO3 layer was provided as an electrode, the LaSrMnO layer was provided as a ferromagnetic layer, the GdCaBaMnO layer was provided as a transition layer, the La0.7Sr0.3MnO3/Ni0.81Fe0.19/Co0.5Fe0.5 layer was provided as a free magnetic layer, the Al2O3 layer was provided as a non-magnetic layer, and the Co0.5Fe0.5/Ru/Co0.5Fe0.5/IrMn layer was provided a fixed magnetic layer.
Herein, the magnetic multilayer film of Ni0.81Fe0.19(20)/Co0.5Fe0.5(1)/Al2O3(1.5)/Co0.5Fe0.5(9)/Ru(0.9)/Co0.5Fe0.5(9)/IrMn(15) formed a magnetoresistive changing part having a TMR type configuration.
Al2O3 as the non-magnetic insulation layer was manufactured by forming an Al film, which was subjected to oxidation, followed by post-oxidation processing. During this step, multi-stages of Al (0.4 nm) film formation, natural oxidation, Al (0.3 nm) film formation, natural oxidation, Al (0.3 nm) film formation and natural oxidation was conducted. Al2O3 after the oxidation had a film thickness of 1.5 nm.
When a voltage 0.1 V≦V≦20 V was applied between S-W terminals, about at least 20% of difference in resistance could be detected between the B-S terminals of all samples, which showed the formation of desired devices.
An integrated memory was manufactured with memory devices having a basic configuration as shown in
The sample included a device having a cross-sectional area of 0.2 μm×0.3 μm, and had the shape of
Word lines and bit lines were all made of Cu.
By the application of a voltage using the word lines and the bit lines and by the application of a magnetic field using the word lines, writing was performed concurrently in eight devices in eight blocks in accordance with information through the magnetization reversal of the respective free magnetic layers, and a 8-bit signal was recorded for each writing operation. Next, a gate of a CMOS that was formed as a pass transistor was turned ON for one device per each block, and a sense current was allowed to flow between P-F, i.e., between a sense line and a bit line. During this step, voltages occurred at bit lines, devices and field effect transistors (FETs) in each block were compared with dummy voltages by a comparator, and 8-bit information was read out concurrently from the output voltage of each device.
Integrated memories were manufactured, in which a ratio between a long axis and a short axis of the free magnetic layer was set at 1.5:1 (short axis: 0.2 μm) and the shape was changed as in
V0=[Vi×(Rv+Rc)]/(Ri+Rv+Rc)
Since the magnetoresistive device portion has different resistances of Rvp and Rvap depending on parallel and antiparallel states of the magnetization direction of magnetic layers, the magnitude of V0 varies in accordance with the change in resistance of the magnetoresistive device portion. Herein, it is assumed that Rvp<Rvap. From this, the above formula can be reformulated as follows:
V0p=[Vi×(Rvp+Rc)]/(Ri+Rvp+Rc)
V0ap=[Vi×(Rvap+Rc)]/(Ri+Rvap+Rc)
Thereby, the relationship V0p<V0ap can be obtained.
When the threshold voltage V of the gate portion of the field effect transistor FET1 (82) is set within the range of V0p<V<V0ap, the operation of the field effect transistor FET1 can be controlled in accordance with the memory of the magnetoresistive device portion.
For example, in the case of using a logical circuit as a load circuit 31, this device can be used as a non-volatile programmable device. Furthermore, in the case of using the load circuit as a display circuit device, this device can be used as a non-volatile storage device for a still image. Furthermore, a plurality of these circuits may be integrated to be used as a system LSI. Herein, in
As described above, according to the present invention, at least one transition layer, at least one electrode and at least one free magnetic layer are included, and at least one of the free magnetic layers is coupled magnetically with the transition layer, and the transition layer undergoes at least magnetic phase change showing ferromagnetism by injecting or inducing electrons or holes, whereby a magnetization direction of the free magnetic layer changes. This configuration is applicable to a magnetic memory that records/reads out magnetization information of the free magnetic layer and various magnetic devices that utilize a resistance change of the magnetoresistive effect portion. Thus, this configuration can enhance the characteristics of a reproduction head of a magnetic recording apparatus used for conventional information communication terminals, such as a magneto-optical disk, a hard disk, a digital data streamer (DDS) and a digital VTR, a cylinder, a magnetic sensor for sensing a rotation speed of a vehicle, a magnetic memory (MRAM), a stress/acceleration sensor that senses a change in stress or acceleration, a thermal sensor, a chemical reaction sensor or the like.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2003-338250 | Sep 2003 | JP | national |
