In this paper,the giant magnetoresistance(GMR)multilayer sensor is fabricated with a Wheatstone bridge,and it exhibits excellent performance with a sensitivity of 2.8349 mV/(V/Oe)(1 Oe=79.5775 A·m^-1)and a satura...In this paper,the giant magnetoresistance(GMR)multilayer sensor is fabricated with a Wheatstone bridge,and it exhibits excellent performance with a sensitivity of 2.8349 mV/(V/Oe)(1 Oe=79.5775 A·m^-1)and a saturation field of 26 Oe along the sensitive axis.The GMR sensor is also characterized in a high magnetic field.The sensitivity decreases from 2.8349 mV/(V/Oe)at an angle of 0°to 0.0175 mV/(V/Oe)at an angle of 90°.Then,the sensor is placed in a series of rotating magnetic fields.We propose a model to express the output characteristics of the GMR multilayer sensor.The transfer curves of the sensor can be shown as two exactly symmetrical circles with an increasing radius when the magnetic field increases.The experimental results are consistent with the simulation results of the model.The advantage of this model is that it is simpler and more intuitive.展开更多
We fabricated flexible spin valves on polyvinylidene fluoride(PVDF) membranes and investigated the influence of thermal deformation of substrates on the giant magnetoresistance(GMR) behaviors. The large magnetostr...We fabricated flexible spin valves on polyvinylidene fluoride(PVDF) membranes and investigated the influence of thermal deformation of substrates on the giant magnetoresistance(GMR) behaviors. The large magnetostrictive Fe_(81)Ga_(19)(Fe Ga) alloy and the low magnetostrictive Fe_(19)Ni_(81)(Fe Ni) alloy were selected as the free and pinned ferromagnetic layers.In addition, the exchange bias(EB) of the pinned layer was set along the different thermal deformation axes α_(31) or α_(32) of PVDF. The GMR ratio of the reference spin valves grown on Si intrinsically increases with lowering temperature due to an enhancement of spontaneous magnetization. For flexible spin valves, when decreasing temperature, the anisotropic thermal deformation of PVDF produces a uniaxial anisotropy along the α_(32) direction, which changes the distribution of magnetic domains. As a result, the GMR ratio at low temperature for spin valves with EB α_(32)becomes close to that on Si, but for spin valves with EB α_(31)is far away from that on Si. This thermal effect on GMR behaviors is more significant when using magnetostrictive Fe Ga as the free layer.展开更多
Ni-Fe/Cu/Co/Cu multilayered nanowire arrays were electrodeposited into anodic aluminum oxide template by using dual-bath method at room temperature. Scanning electron microscopy and transmission electron microscopy we...Ni-Fe/Cu/Co/Cu multilayered nanowire arrays were electrodeposited into anodic aluminum oxide template by using dual-bath method at room temperature. Scanning electron microscopy and transmission electron microscopy were used to characterize the morphology and structure of the multilayered nanowire arrays. Vibrating sample magnetometer and physical property measurement system were used to measure their magnetic and giant magnetoresistance (GMR) properties. The effect of sub-layer thickness on the magnetic and GMR properties was investigated. The results indicate that magnetic properties of electmdeposited nanowires are not affected obviously by Cu layer thickness, while magnetic layers (Ni-Fe and Co layers) have significant influence. In addition, GMR ratio presents an oscillatory behavior as Cu layer thickness changes. The magnetic and GMR properties of the multilayered nanowire arrays are optimum at room temperature for the material structure of Ni-Fe (25 nm)/Cu (15 nm)/Co (25 nm)/Cu (15 nm) with 30 deposition cycles.展开更多
The structure and microfabrication,the detecting theory and the way of biomolecular recognition device based on giant magnetoresistance(GMR) effect are introduced,also the signal detecting and processing instrumentati...The structure and microfabrication,the detecting theory and the way of biomolecular recognition device based on giant magnetoresistance(GMR) effect are introduced,also the signal detecting and processing instrumentation are presented. Here the GMR biosensor was fabricated with magnetic tunnel junction(MJT) material.The biomolecular recognition device contains an array of MJT sensors,single MJT sensor size is 10μm×20μm,tunneling magnetoresistance ratio(TMR) at room temperature is 52.2%,the typical values of junction resistance-area product Rs is 2.6 kΩμm^2,detecting sensitivity of this system is about 8×10^(-4) A·m^(-1).Bioadaptation layer of this device was fabricated with PDMS the thickness of which is less than 100 nm.展开更多
We have studied the transport property of the composites (La0.83Sr0.17 MnO3)1-x(ITO)x [ITO=(In2O3)0.95 (SNO2)0.05], which were fabricated by mechanically mixing La0.83Sr0.17MnO3 and ITO grains. A giant positiv...We have studied the transport property of the composites (La0.83Sr0.17 MnO3)1-x(ITO)x [ITO=(In2O3)0.95 (SNO2)0.05], which were fabricated by mechanically mixing La0.83Sr0.17MnO3 and ITO grains. A giant positive magnetoresistance (PMR) has been observed above the Curie temperature Tc for samples with x around 0.40, in addition to the negative magnetoresistanee related to spin-dependent interracial tunnelling below To. For (La0.83Sr0.17MnO3)0.6(ITO)0.4, the magnetoresistive ratio for the PMR can reach 39.3% under a magnetic field H=2.24×10^5A/m. Theoretical analysis suggests that the magnetic-field-induced broadening of the p-n barrier between both kinds of grains and the density of the p-n heterostructures should be responsible for the PMR behaviour.展开更多
The transport property of electrons tunneling through arrays of magnetic and electric barriers is studied in silicene. In the tunneling transmission spectrum, the spin-valley-dependent filtered states can be achieved ...The transport property of electrons tunneling through arrays of magnetic and electric barriers is studied in silicene. In the tunneling transmission spectrum, the spin-valley-dependent filtered states can be achieved in an incident energy range which can be controlled by the electric gate voltage. For the parallel magnetization configuration, the transmission is asymmetric with respect to the incident angle θ, and electrons with a very large negative incident angle can always transmit in propagating modes for one of the spin-valley filtered states under a certain electromagnetic condition. But for the antiparallel configuration, the transmission is symmetric about θ and there is no such transmission channel. The difference of the transmission between the two configurations leads to a giant tunneling magnetoresistance (TMR) effect. The TMR can reach to 100% in a certain Fermi energy interval around the electrostatic potential. This energy interval can be adjusted significantly by the magnetic field and/or electric gate voltage. The results obtained may be useful for future valleytronic and spintronic applications, as well as magnetoresistance device based on silicene.展开更多
Prx(Co40Ag60)100-x (x=0, 0.5, 1, 1.5, 2, 3) granular films have been prepared by DC magneto controlled sputtering method. The XRD data indicated that Pr element favors the (111) plane preferential orientation. M...Prx(Co40Ag60)100-x (x=0, 0.5, 1, 1.5, 2, 3) granular films have been prepared by DC magneto controlled sputtering method. The XRD data indicated that Pr element favors the (111) plane preferential orientation. Magnetic measurements indicate that the average size of magnetic particles decreases as Pr content increases. For relatively low addition of Pr to CoAg granular films, Pr element can enhance GMR value and a peak value of about -14.3% is obtained at x=1.展开更多
A special Fe3O4nanoparticles–graphene(Fe3O4–GN) composite as a magnetic label was employed for biodetection using giant magnetoresistance(GMR) sensors with a Wheatstone bridge. The Fe3O4–GN composite exhibits a...A special Fe3O4nanoparticles–graphene(Fe3O4–GN) composite as a magnetic label was employed for biodetection using giant magnetoresistance(GMR) sensors with a Wheatstone bridge. The Fe3O4–GN composite exhibits a strong ferromagnetic behavior with the saturation magnetization MS of approximately 48 emu/g, coercivity HC of 200 Oe, and remanence Mr of 8.3 emu/g, leading to a large magnetic fringing field. However, the Fe3O4 nanoparticles do not aggregate together, which can be attributed to the pinning and separating effects of graphene sheet to the magnetic particles. The Fe3O4–GN composite is especially suitable for biodetection as a promising magnetic label since it combines two advantages of large fringing field and no aggregation. As a result, the concentration x dependence of voltage difference |?V| between detecting and reference sensors undergoes the relationship of |?V| = 240.5 lgx + 515.2 with an ultralow detection limit of 10 ng/mL(very close to the calculated limit of 7 ng/mL) and a wide detection range of 4 orders.展开更多
The giant magnetoresistance (GMR) in magnetic multilayers with current in the plane of the layers is studied by using the quantum-statistical Green's function approach, in which the effects of the interfacial roug...The giant magnetoresistance (GMR) in magnetic multilayers with current in the plane of the layers is studied by using the quantum-statistical Green's function approach, in which the effects of the interfacial roughness and magnetization configuration on the GMR are included. It is shown that the maximal GMR first increases and then decreases with increasing interfacial roughness, exhibiting a peak at an optimum value of interfacial roughness. An approximately linear dependence of GMR on is obtained, where is the angle between magnetizations of the two successive ferromagnetic layers. Furthermore, the maximal GMR is found to increase with increasing the number of bilayers.展开更多
GMR effect of multilayers of bcc-Fe(M)(M=Co, Ni) alloy and Cu layers has been investigated. The maximum MR ratio is found at 1.1 nm Fe(Co) and 1.3~1.4 nm Cu layer thickness in [Fe(Co)/CuJ, and at 1.6 nm Fe(Ni) and 1....GMR effect of multilayers of bcc-Fe(M)(M=Co, Ni) alloy and Cu layers has been investigated. The maximum MR ratio is found at 1.1 nm Fe(Co) and 1.3~1.4 nm Cu layer thickness in [Fe(Co)/CuJ, and at 1.6 nm Fe(Ni) and 1.4 nm Cu layer thickness in [Fe(Ni)/Cu]. Under the optimum annealing condition, the MR ratio increases up to 50% and 38% for Fe(Co) and Fe(Ni) systems, respectively. The origin of the increase of GMR is discussed, taking the progress of preferred orientation of Fe(Co)[100] or Fe(Ni)[100] by anneahng into account.展开更多
Taking into account the quantum size effects and considering three types of scattering from bulk impurities,rough surface and rough interfaces, we use quantum-statistical Green's function approach and Kubo theory ...Taking into account the quantum size effects and considering three types of scattering from bulk impurities,rough surface and rough interfaces, we use quantum-statistical Green's function approach and Kubo theory to calculate the electronic conductivity and the giant magnetoresistance in magnetic multilayered cylindrical systems. It is found that in the limit of weakly scattering from impurities surface and interfaces, the total conductivity is given by a sum of conductivities of all the subbands and two spin-channels. For each subband and each spin-channel the scattering rate due to the impurities, surface and interfaces is added up.展开更多
A phenomenological theoretical model for magnetic multilayer based on Boltzmann equation and Fuchs-Sondheimer theory is studied. An oscillatory transmission coefficient (Ts) is introduced into the boundary conditions ...A phenomenological theoretical model for magnetic multilayer based on Boltzmann equation and Fuchs-Sondheimer theory is studied. An oscillatory transmission coefficient (Ts) is introduced into the boundary conditions to simulate the alternate ferromagnetic and anti-ferromagnetic coupling between the magnetic layers. The transmission coefficient has an oscillatory factor relating to the thickness of space layer. Other effects such as interface roughness on Ts are also taken into account. The numerical results for [Fe/Cr]n multilayer agree with the experimental data very well, both in the period and range of osciallation, which is leaded by the dependence of giant magnetoresistance(GMR) on layer thickness of space layer.展开更多
Granular CoxCu1-x alloy films were prepared by electrodeposition at room temperature directly onto semiconducting Si substrate. X-ray diffraction (XRD) revealed that the as-deposited films formed single phase metastab...Granular CoxCu1-x alloy films were prepared by electrodeposition at room temperature directly onto semiconducting Si substrate. X-ray diffraction (XRD) revealed that the as-deposited films formed single phase metastable fcc alloy structure. The fcc lattice parameter α was found to decrease linearly with increasing Co concentration x in the studied range. The giant magnetoresistance (GMR) of the films was improved after annealing. Pure Co fcc diffraction peaks were observed in the diffractogram of the annealed sample, indicating phase separation occurred upon annealing. The optimal annealing temperature was 450℃. The maximum of magnetoresistance (MR) ratio 8.21% was obtained for the Co20Cu80 thin film after annealing at 450℃ for 1 h. The saturation field decreased upon annealing in the MR curves of Co20Cu80 film.展开更多
The magnetoresistance behavior and the magnetization reversal mode of NiFe/Cu/CoFe/IrMn spin valve giant magnetoresistance (SV-GMR) in nanoscale were investigated experimentally and theoretically by nanosized magnet...The magnetoresistance behavior and the magnetization reversal mode of NiFe/Cu/CoFe/IrMn spin valve giant magnetoresistance (SV-GMR) in nanoscale were investigated experimentally and theoretically by nanosized magnetic simulation methods. Based on the Landau-Lifshitz-Gilbert equation, a model with a special gridding was proposed to calculate the giant magnetoresistance ratio (MR) and investigate the magnetization reversal mode. The relationship between MR and the external magnetic field was obtained and analyzed. Studies into the variation of the magnetization distribution reveal that the magnetization reversal mode, that is, the jump variation mode for NiFe/Cu/CoFe/IrMn, depends greatly on the antiferromagnetic coupling behavior between the pinned layer and the antiferromagnetic layer. It is also found that the switching field is almost linear with the exchange coefficient.展开更多
Pseudo-spin-valve (PSV) sandwiches using amorphous CoNbZr alloy as soft magnetic layer were fabricated by magnetron sputtering. The giant magnetoresistance (GMR) and its dependence on the thickness of magnetic layer w...Pseudo-spin-valve (PSV) sandwiches using amorphous CoNbZr alloy as soft magnetic layer were fabricated by magnetron sputtering. The giant magnetoresistance (GMR) and its dependence on the thickness of magnetic layer were investigated. Anti-parallel magnetization alignments were observed in the samples with very thin CoNbZr thickness (2-4 nm) and a maximum GMR ratio of 6.5% was obtained. The Camley-Barnas semiclassical model was extended for amorphous layer based magnetic sandwiches by considering that the mixed layers exist between the ferromagnetic and nonmagnetic layer. The calculated results agree with the experimental results very well, indicating that the new model gives a more realistic picture of the physical processes that take place in the magnetic sandwiches. Moreover, the calculated results for amorphous sandwiches also clarify that the occurrence of maximum GMR at very small thickness of amorphous layer is ascribed to the short mean-free-path in amorphous materials.展开更多
基金Project supported by the National Key Research and Development Program of China(Grant No.2018YFF01010701)the Natural Science Foundation of Zhejiang Province,China(Grant No.LQ17F010004)the National Natural Science Foundation of China(Grant No.61741506)
文摘In this paper,the giant magnetoresistance(GMR)multilayer sensor is fabricated with a Wheatstone bridge,and it exhibits excellent performance with a sensitivity of 2.8349 mV/(V/Oe)(1 Oe=79.5775 A·m^-1)and a saturation field of 26 Oe along the sensitive axis.The GMR sensor is also characterized in a high magnetic field.The sensitivity decreases from 2.8349 mV/(V/Oe)at an angle of 0°to 0.0175 mV/(V/Oe)at an angle of 90°.Then,the sensor is placed in a series of rotating magnetic fields.We propose a model to express the output characteristics of the GMR multilayer sensor.The transfer curves of the sensor can be shown as two exactly symmetrical circles with an increasing radius when the magnetic field increases.The experimental results are consistent with the simulation results of the model.The advantage of this model is that it is simpler and more intuitive.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11374312,51401230,51522105,and 51471101)the Ningbo Science and Technology Innovation Team,China(Grant No.2015B11001)
文摘We fabricated flexible spin valves on polyvinylidene fluoride(PVDF) membranes and investigated the influence of thermal deformation of substrates on the giant magnetoresistance(GMR) behaviors. The large magnetostrictive Fe_(81)Ga_(19)(Fe Ga) alloy and the low magnetostrictive Fe_(19)Ni_(81)(Fe Ni) alloy were selected as the free and pinned ferromagnetic layers.In addition, the exchange bias(EB) of the pinned layer was set along the different thermal deformation axes α_(31) or α_(32) of PVDF. The GMR ratio of the reference spin valves grown on Si intrinsically increases with lowering temperature due to an enhancement of spontaneous magnetization. For flexible spin valves, when decreasing temperature, the anisotropic thermal deformation of PVDF produces a uniaxial anisotropy along the α_(32) direction, which changes the distribution of magnetic domains. As a result, the GMR ratio at low temperature for spin valves with EB α_(32)becomes close to that on Si, but for spin valves with EB α_(31)is far away from that on Si. This thermal effect on GMR behaviors is more significant when using magnetostrictive Fe Ga as the free layer.
基金Supported by the Natural Science Foundation of Tianjin,China(08JCZDJC17400)
文摘Ni-Fe/Cu/Co/Cu multilayered nanowire arrays were electrodeposited into anodic aluminum oxide template by using dual-bath method at room temperature. Scanning electron microscopy and transmission electron microscopy were used to characterize the morphology and structure of the multilayered nanowire arrays. Vibrating sample magnetometer and physical property measurement system were used to measure their magnetic and giant magnetoresistance (GMR) properties. The effect of sub-layer thickness on the magnetic and GMR properties was investigated. The results indicate that magnetic properties of electmdeposited nanowires are not affected obviously by Cu layer thickness, while magnetic layers (Ni-Fe and Co layers) have significant influence. In addition, GMR ratio presents an oscillatory behavior as Cu layer thickness changes. The magnetic and GMR properties of the multilayered nanowire arrays are optimum at room temperature for the material structure of Ni-Fe (25 nm)/Cu (15 nm)/Co (25 nm)/Cu (15 nm) with 30 deposition cycles.
文摘The structure and microfabrication,the detecting theory and the way of biomolecular recognition device based on giant magnetoresistance(GMR) effect are introduced,also the signal detecting and processing instrumentation are presented. Here the GMR biosensor was fabricated with magnetic tunnel junction(MJT) material.The biomolecular recognition device contains an array of MJT sensors,single MJT sensor size is 10μm×20μm,tunneling magnetoresistance ratio(TMR) at room temperature is 52.2%,the typical values of junction resistance-area product Rs is 2.6 kΩμm^2,detecting sensitivity of this system is about 8×10^(-4) A·m^(-1).Bioadaptation layer of this device was fabricated with PDMS the thickness of which is less than 100 nm.
基金Project supported by the National Natural Science Foundation of China (Grant No 20473038), the Foundation of High-Tech Project in Jiangsu province, China (Grant No BG-2005401).
文摘We have studied the transport property of the composites (La0.83Sr0.17 MnO3)1-x(ITO)x [ITO=(In2O3)0.95 (SNO2)0.05], which were fabricated by mechanically mixing La0.83Sr0.17MnO3 and ITO grains. A giant positive magnetoresistance (PMR) has been observed above the Curie temperature Tc for samples with x around 0.40, in addition to the negative magnetoresistanee related to spin-dependent interracial tunnelling below To. For (La0.83Sr0.17MnO3)0.6(ITO)0.4, the magnetoresistive ratio for the PMR can reach 39.3% under a magnetic field H=2.24×10^5A/m. Theoretical analysis suggests that the magnetic-field-induced broadening of the p-n barrier between both kinds of grains and the density of the p-n heterostructures should be responsible for the PMR behaviour.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11547249,51501102,and 11647157)the Science Foundation for Excellent Youth Doctors of Three Gorges University,China(Grant No.KJ2014B076)
文摘The transport property of electrons tunneling through arrays of magnetic and electric barriers is studied in silicene. In the tunneling transmission spectrum, the spin-valley-dependent filtered states can be achieved in an incident energy range which can be controlled by the electric gate voltage. For the parallel magnetization configuration, the transmission is asymmetric with respect to the incident angle θ, and electrons with a very large negative incident angle can always transmit in propagating modes for one of the spin-valley filtered states under a certain electromagnetic condition. But for the antiparallel configuration, the transmission is symmetric about θ and there is no such transmission channel. The difference of the transmission between the two configurations leads to a giant tunneling magnetoresistance (TMR) effect. The TMR can reach to 100% in a certain Fermi energy interval around the electrostatic potential. This energy interval can be adjusted significantly by the magnetic field and/or electric gate voltage. The results obtained may be useful for future valleytronic and spintronic applications, as well as magnetoresistance device based on silicene.
基金Funded by the National Natural Science Foundation of Guangxi and Guangxi Key Laboratory of Information Materials Foundation (No.0575093&0710908-11-Z)
文摘Prx(Co40Ag60)100-x (x=0, 0.5, 1, 1.5, 2, 3) granular films have been prepared by DC magneto controlled sputtering method. The XRD data indicated that Pr element favors the (111) plane preferential orientation. Magnetic measurements indicate that the average size of magnetic particles decreases as Pr content increases. For relatively low addition of Pr to CoAg granular films, Pr element can enhance GMR value and a peak value of about -14.3% is obtained at x=1.
基金supported by the National Natural Science Foundation of China(Grant Nos.11074040,11504192,11674187,11604172,and 51403114)the Natural Science Foundation of Shandong Province,China(Grant Nos.ZR2012FZ006 and BS2014CL010)the China Postdoctoral Science Foundation(Grant Nos.2014M551868 and 2015M570570)
文摘A special Fe3O4nanoparticles–graphene(Fe3O4–GN) composite as a magnetic label was employed for biodetection using giant magnetoresistance(GMR) sensors with a Wheatstone bridge. The Fe3O4–GN composite exhibits a strong ferromagnetic behavior with the saturation magnetization MS of approximately 48 emu/g, coercivity HC of 200 Oe, and remanence Mr of 8.3 emu/g, leading to a large magnetic fringing field. However, the Fe3O4 nanoparticles do not aggregate together, which can be attributed to the pinning and separating effects of graphene sheet to the magnetic particles. The Fe3O4–GN composite is especially suitable for biodetection as a promising magnetic label since it combines two advantages of large fringing field and no aggregation. As a result, the concentration x dependence of voltage difference |?V| between detecting and reference sensors undergoes the relationship of |?V| = 240.5 lgx + 515.2 with an ultralow detection limit of 10 ng/mL(very close to the calculated limit of 7 ng/mL) and a wide detection range of 4 orders.
文摘The giant magnetoresistance (GMR) in magnetic multilayers with current in the plane of the layers is studied by using the quantum-statistical Green's function approach, in which the effects of the interfacial roughness and magnetization configuration on the GMR are included. It is shown that the maximal GMR first increases and then decreases with increasing interfacial roughness, exhibiting a peak at an optimum value of interfacial roughness. An approximately linear dependence of GMR on is obtained, where is the angle between magnetizations of the two successive ferromagnetic layers. Furthermore, the maximal GMR is found to increase with increasing the number of bilayers.
基金Ministry of Education, Science, Sports and Culture under Grantin-Aid for Scielltific Research on Priority Areas (A), Japan!(No.
文摘GMR effect of multilayers of bcc-Fe(M)(M=Co, Ni) alloy and Cu layers has been investigated. The maximum MR ratio is found at 1.1 nm Fe(Co) and 1.3~1.4 nm Cu layer thickness in [Fe(Co)/CuJ, and at 1.6 nm Fe(Ni) and 1.4 nm Cu layer thickness in [Fe(Ni)/Cu]. Under the optimum annealing condition, the MR ratio increases up to 50% and 38% for Fe(Co) and Fe(Ni) systems, respectively. The origin of the increase of GMR is discussed, taking the progress of preferred orientation of Fe(Co)[100] or Fe(Ni)[100] by anneahng into account.
文摘Taking into account the quantum size effects and considering three types of scattering from bulk impurities,rough surface and rough interfaces, we use quantum-statistical Green's function approach and Kubo theory to calculate the electronic conductivity and the giant magnetoresistance in magnetic multilayered cylindrical systems. It is found that in the limit of weakly scattering from impurities surface and interfaces, the total conductivity is given by a sum of conductivities of all the subbands and two spin-channels. For each subband and each spin-channel the scattering rate due to the impurities, surface and interfaces is added up.
文摘A phenomenological theoretical model for magnetic multilayer based on Boltzmann equation and Fuchs-Sondheimer theory is studied. An oscillatory transmission coefficient (Ts) is introduced into the boundary conditions to simulate the alternate ferromagnetic and anti-ferromagnetic coupling between the magnetic layers. The transmission coefficient has an oscillatory factor relating to the thickness of space layer. Other effects such as interface roughness on Ts are also taken into account. The numerical results for [Fe/Cr]n multilayer agree with the experimental data very well, both in the period and range of osciallation, which is leaded by the dependence of giant magnetoresistance(GMR) on layer thickness of space layer.
基金This work was supported by the National Natural Science Foundation of China under grant No.50071039,50271046supported by the United Academy of Education Ministry,Tianjin University and Nankai University.
文摘Granular CoxCu1-x alloy films were prepared by electrodeposition at room temperature directly onto semiconducting Si substrate. X-ray diffraction (XRD) revealed that the as-deposited films formed single phase metastable fcc alloy structure. The fcc lattice parameter α was found to decrease linearly with increasing Co concentration x in the studied range. The giant magnetoresistance (GMR) of the films was improved after annealing. Pure Co fcc diffraction peaks were observed in the diffractogram of the annealed sample, indicating phase separation occurred upon annealing. The optimal annealing temperature was 450℃. The maximum of magnetoresistance (MR) ratio 8.21% was obtained for the Co20Cu80 thin film after annealing at 450℃ for 1 h. The saturation field decreased upon annealing in the MR curves of Co20Cu80 film.
基金financially supported by the National Natural Science Foundation of China (Nos. 61025021and 60936002)the National Key Project of Scienceand Technology of China (Nos. 2009ZX02023-001-3 and 2011ZX02403-002)the Independent Scientific Research of Tsinghua University (No. 2010THZ0)
文摘The magnetoresistance behavior and the magnetization reversal mode of NiFe/Cu/CoFe/IrMn spin valve giant magnetoresistance (SV-GMR) in nanoscale were investigated experimentally and theoretically by nanosized magnetic simulation methods. Based on the Landau-Lifshitz-Gilbert equation, a model with a special gridding was proposed to calculate the giant magnetoresistance ratio (MR) and investigate the magnetization reversal mode. The relationship between MR and the external magnetic field was obtained and analyzed. Studies into the variation of the magnetization distribution reveal that the magnetization reversal mode, that is, the jump variation mode for NiFe/Cu/CoFe/IrMn, depends greatly on the antiferromagnetic coupling behavior between the pinned layer and the antiferromagnetic layer. It is also found that the switching field is almost linear with the exchange coefficient.
基金Project (90306015) supported by NSFC Project supported by Youth Foundation of Science and Technology of UESTC
文摘Pseudo-spin-valve (PSV) sandwiches using amorphous CoNbZr alloy as soft magnetic layer were fabricated by magnetron sputtering. The giant magnetoresistance (GMR) and its dependence on the thickness of magnetic layer were investigated. Anti-parallel magnetization alignments were observed in the samples with very thin CoNbZr thickness (2-4 nm) and a maximum GMR ratio of 6.5% was obtained. The Camley-Barnas semiclassical model was extended for amorphous layer based magnetic sandwiches by considering that the mixed layers exist between the ferromagnetic and nonmagnetic layer. The calculated results agree with the experimental results very well, indicating that the new model gives a more realistic picture of the physical processes that take place in the magnetic sandwiches. Moreover, the calculated results for amorphous sandwiches also clarify that the occurrence of maximum GMR at very small thickness of amorphous layer is ascribed to the short mean-free-path in amorphous materials.