Pseudo spin valves（SVs） exhibiting perpendicular magnetic anisotropy were prepared by magnetron sputtering. Magnetization measurements of the Co/Pt multilayers were performed to select the reference and free layers....Pseudo spin valves（SVs） exhibiting perpendicular magnetic anisotropy were prepared by magnetron sputtering. Magnetization measurements of the Co/Pt multilayers were performed to select the reference and free layers. The selection criteria are square magnetic hysteresis loops, weaker current shunting effect, and proper coercivity. The optimal reference layer and free layer are Pt（5.0 nm）/[Co（0.4 nm）/Pt（0.6 nm）]3/Co（0.4 nm）/Cu（3.0 nm）and Cu（3.0 nm）/[Co（0.4 nm）/Pt（1.5 nm）]4, respectively.The resulting pseudo SV exhibits two well-separated hysteresis loops when the field is applied perpendicular to the film plane. The minor hysteresis loop corresponding to the free layer shifts toward negative direction of the magnetic field axis, indicating ferromagnetic interlayer exchange coupling between the two magnetic layers. The coupling also enhances the coercivity（HC） of both layers. The perpendicular giant magnetoresistance（GMR） of 2.7 % is achieved with current in plane measurement. The GMR first increases when Pt seed layer is thickened, reaches a maximum of 3.0 % at 4 nm and then decreases with the further increase of thickness. But thicker Cu spacer layer always lowers the GMR of the SV.展开更多
A new tamping device which is driven by an electrohydraulic exciter was proposed to overcome the limitations of mechanically driven devices.The double-rod oscillation cylinder drives the tamping arm to realize vibrati...A new tamping device which is driven by an electrohydraulic exciter was proposed to overcome the limitations of mechanically driven devices.The double-rod oscillation cylinder drives the tamping arm to realize vibration.A new spin valve was designed in order to fulfill dynamic state requirements of the oscillation cylinder.Parametric analysis was carried out by establishing mathematic model.Then,the relationships among the structure of valve port and the frequency,amplitude,output shock force of the cylinder were researched.An experimental device of the electrohydraulic exciter was established to validate the theoretical results.The signals were acquired by AVANT dynamic signal analyser of vibration.The results show that new tamping device can satisfy all kinds of complex working conditions with the flexible adjustment of frequency and amplitude.展开更多
Interface engineering in device fabrication is a significant but complicated issue.Although great successes have been achieved by conventional physical in situ or ex situ methods,it still suffers from complicated proc...Interface engineering in device fabrication is a significant but complicated issue.Although great successes have been achieved by conventional physical in situ or ex situ methods,it still suffers from complicated procedures.In this work,we present a facile method for fabricating phthalocyanine(Pc)-based two-dimensional conductive metal–organic framework(MOF)films.Based on PcM-Cu(M=Ni,Cu,H_(2))MOF films,spin valves with a vertical configuration of La_(0.67)Sr_(0.33)MnO_(3)/PcM-Cu MOFs/Co were constructed successfully,and exhibited notably high negative magnetoresistance(MR)up to -22% at 50 K.The penetrated Co atoms coordinated with the dehydrogenated hydroxy groups in the MOFs resulting in an antiferromagnetic layer of the PcM-Cu-Co hybrid structure.Interestingly,a significant exchange bias effect was demonstrated at the PcM-Cu MOF/Co interface,beneficial for the MR behavior.Thus,our present study provides new insights into developing high-performance organic spin valves via de novo molecular design.展开更多
Molecular spintronics is an emerging field which evoked wide research attention since the first molecule-based spintronic device has been reported at 2002. Due to the active study over the last few years, it is found ...Molecular spintronics is an emerging field which evoked wide research attention since the first molecule-based spintronic device has been reported at 2002. Due to the active study over the last few years, it is found that the interfaces in spintronic device, so called spinterface, is of critical importance for many key issues in molecular spintronics, such as enhancing spin injection, lengthening spin transport distance, as well as manipulating spin signals in molecular spintronic devices. Here in this review, recent studies regarding spinterface in molecular devices, especially those impressive efforts devoted on spin manipulation, have been systematically summarized and discussed.展开更多
A brief review is presented,which includes the direct current,alternate current,electrical and thermoelectrical transport as well as spin transfer effect in a variety of spin-based nanostructures such as the magnetic ...A brief review is presented,which includes the direct current,alternate current,electrical and thermoelectrical transport as well as spin transfer effect in a variety of spin-based nanostructures such as the magnetic tunnel junction(MTJ),ferromagnet(FM)-quantum dot(QD)/FM-FM,double barrier MTJ,FM-marginal Fermi liquid-FM,FM-unconventional superconductor-FM(FUSF),quantum ring and optical spin-field-effect transistor.The magnetoresistances in those structures,spin accumulation effect in FM-QD-FM and FUSF systems,spin injection and spin filter into semiconductor,spin transfer effect,photon-assisted spin transport,magnonassisted tunneling,electron-electron interaction effect on spin transport,laser-controlled spin dynamics,and thermoelectrical spin transport are discussed.展开更多
Understanding the stability and current-carrying capacity of graphene spintronic devices is key to their applications in graphene channel-based spin current sensors,spin-torque oscillators,and potential spin-integrate...Understanding the stability and current-carrying capacity of graphene spintronic devices is key to their applications in graphene channel-based spin current sensors,spin-torque oscillators,and potential spin-integrated circuits.However,despite the demonstrated high current densities in exfoliated graphene,the current-carrying capacity of large-scale chemical vapor deposited(CVD)graphene is not established.Particularly,the grainy nature of chemical vapor deposited graphene and the presence of a tunnel barrier in CVD graphene spin devices pose questions about the stability of high current electrical spin injection.In this work,we observe that despite structural imperfections,CVD graphene sustains remarkably highest currents of 5.2×10^(8)A/cm^(2),up to two orders higher than previously reported values in multilayer CVD graphene,with the capacity primarily dependent upon the sheet resistance of graphene.Furthermore,we notice a reversible regime,up to which CVD graphene can be operated without degradation with operating currents as high as 108 A/cm^(2),significantly high and durable over long time of operation with spin valve signals observed up to such high current densities.At the same time,the tunnel barrier resistance can be modified by the application of high currents.Our results demonstrate the robustness of large-scale CVD graphene and bring fresh insights for engineering and harnessing pure spin currents for innovative device applications.展开更多
A single-molecule magnet is a long-sought-after nanoscale component because it can enable us to miniaturize nonvolatile memory storage devices.The signature of a single-molecule magnet is switching between two bistabl...A single-molecule magnet is a long-sought-after nanoscale component because it can enable us to miniaturize nonvolatile memory storage devices.The signature of a single-molecule magnet is switching between two bistable magnetic ground states under an external magnetic field.Based on this feature,we theoretically investigate a magnetic-fieldcontrolled reversible resistance change active at low temperatures in a molecular magnetic tunnel junction,which consists of a single-molecule magnet sandwiched between a ferromagnetic electrode and a normal metal electrode.Our numerical results demonstrate that the molecular magnetism orientation can be manipulated by magnetic fields to be parallel/antiparallel to the ferromagnetic electrode magnetization.Moreover,different magnetic configurations can be“read out”based on different resistance states or different spin polarization parameters in the current spectrum,even in the absence of a magnetic field.Such an external magnetic field-controlled resistance state switching effect is similar to that in traditional spin valve devices.The difference between the two systems is that one of the ferromagnetic layers in the original device has been replaced by a magnetic molecule.This proposed scheme provides the possibility of better control of the spin freedom of electrons in molecular electrical devices,with potential applications in future high-density nonvolatile memory devices.展开更多
Magnetic tunnel junctions(MTJs),a prominent type of spintronic device based on the spin valve effect,have facilitated the development of numerous spintronic applications.The technical appeal for the next-generation MT...Magnetic tunnel junctions(MTJs),a prominent type of spintronic device based on the spin valve effect,have facilitated the development of numerous spintronic applications.The technical appeal for the next-generation MTJ devices has been proposed in two directions:improving device performance by utilizing advanced two-dimensional(2D)ferromagnetic materials or extending device functionalities by exploring the gate-tunable magnetic properties of ferromagnets.Based on the recent development of 2D magnets with the ease of external stimuli,such as electric field,due to their reduced dimensions,reliable prospects for gate-tunable MTJ devices can be achieved,shedding light on the great potential of next-generation MTJs with multiple functionalities for various application environments.While the electrical gate-tunable MTJ device is highly desirable for practical spintronic devices,it has not yet been demonstrated.Here,we demonstrate the experimental realization of a spin valve device by combining a vertical Fe_(3)GeTe_(2)/h-BN/Fe_(3)GeTe_(2) MTJ with an electrolyte gate.The magnetoresistance ratio(MR ratio)of 36%for the intrinsic MTJ confirms the good performance of the device.By electrolyte gating,the tunneling MR ratio of Fe_(3)GeTe_(2)/h-BN/Fe_(3)GeTe_(2) MTJ can be elevated 2.5 times,from 26%to 65%.Importantly,the magnetic fields at which the magnetoresistance switches for the MTJ can be modulated by electrical gating,providing a promising method to control the magnetization configuration of the MTJ.Our work demonstrates a gate-tunable MTJ device toward the possibility for gate-controlled spintronic devices,paving the way for performing 2D magnetism manipulations and exploring innovative spintronic applications.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos. 11174020, 51331002, and 51371027)the Fundamental Research Funds for the Central Universities FRF-SD-12-011A
文摘Pseudo spin valves（SVs） exhibiting perpendicular magnetic anisotropy were prepared by magnetron sputtering. Magnetization measurements of the Co/Pt multilayers were performed to select the reference and free layers. The selection criteria are square magnetic hysteresis loops, weaker current shunting effect, and proper coercivity. The optimal reference layer and free layer are Pt（5.0 nm）/[Co（0.4 nm）/Pt（0.6 nm）]3/Co（0.4 nm）/Cu（3.0 nm）and Cu（3.0 nm）/[Co（0.4 nm）/Pt（1.5 nm）]4, respectively.The resulting pseudo SV exhibits two well-separated hysteresis loops when the field is applied perpendicular to the film plane. The minor hysteresis loop corresponding to the free layer shifts toward negative direction of the magnetic field axis, indicating ferromagnetic interlayer exchange coupling between the two magnetic layers. The coupling also enhances the coercivity（HC） of both layers. The perpendicular giant magnetoresistance（GMR） of 2.7 % is achieved with current in plane measurement. The GMR first increases when Pt seed layer is thickened, reaches a maximum of 3.0 % at 4 nm and then decreases with the further increase of thickness. But thicker Cu spacer layer always lowers the GMR of the SV.
基金Projects(50975252,51275499)supported by the National Natural Science Foundation of ChinaProject(2013CB035404)supported by the National Basic Research Program of ChinaProject(GZKF-201312)supported by Open Foundation of the State Key Laboratory of Fluid Power Transmission and Control,China
文摘A new tamping device which is driven by an electrohydraulic exciter was proposed to overcome the limitations of mechanically driven devices.The double-rod oscillation cylinder drives the tamping arm to realize vibration.A new spin valve was designed in order to fulfill dynamic state requirements of the oscillation cylinder.Parametric analysis was carried out by establishing mathematic model.Then,the relationships among the structure of valve port and the frequency,amplitude,output shock force of the cylinder were researched.An experimental device of the electrohydraulic exciter was established to validate the theoretical results.The signals were acquired by AVANT dynamic signal analyser of vibration.The results show that new tamping device can satisfy all kinds of complex working conditions with the flexible adjustment of frequency and amplitude.
基金financially supported by the National Key Research and Development Program of China(grant no.2017YFA0207500)the National Natural Science Foundation of China(grant nos.51973153 and 11774254).
文摘Interface engineering in device fabrication is a significant but complicated issue.Although great successes have been achieved by conventional physical in situ or ex situ methods,it still suffers from complicated procedures.In this work,we present a facile method for fabricating phthalocyanine(Pc)-based two-dimensional conductive metal–organic framework(MOF)films.Based on PcM-Cu(M=Ni,Cu,H_(2))MOF films,spin valves with a vertical configuration of La_(0.67)Sr_(0.33)MnO_(3)/PcM-Cu MOFs/Co were constructed successfully,and exhibited notably high negative magnetoresistance(MR)up to -22% at 50 K.The penetrated Co atoms coordinated with the dehydrogenated hydroxy groups in the MOFs resulting in an antiferromagnetic layer of the PcM-Cu-Co hybrid structure.Interestingly,a significant exchange bias effect was demonstrated at the PcM-Cu MOF/Co interface,beneficial for the MR behavior.Thus,our present study provides new insights into developing high-performance organic spin valves via de novo molecular design.
基金Project supported by the National Natural Science Foundation of China(Grant No.21673059)the Funds from Ministry of Science and Technology of China(Grant Nos.2017YFA0206600 and 2016YFA0200700)+1 种基金the Instrument Development Project of Chinese Academy of Sciences(Grant No.YJKYYQ20170037)the CAS Pioneer Hundred Talents Program
文摘Molecular spintronics is an emerging field which evoked wide research attention since the first molecule-based spintronic device has been reported at 2002. Due to the active study over the last few years, it is found that the interfaces in spintronic device, so called spinterface, is of critical importance for many key issues in molecular spintronics, such as enhancing spin injection, lengthening spin transport distance, as well as manipulating spin signals in molecular spintronic devices. Here in this review, recent studies regarding spinterface in molecular devices, especially those impressive efforts devoted on spin manipulation, have been systematically summarized and discussed.
基金supported in part by the National Science Fund for Distinguished Young Scholars of China(Grant No. 10625419)the National Natural Science Foundation of China(Grant Nos. 90922033 and 10934008)+1 种基金the Ministry of Science and Technology of China (Grant Nos.2012CB932900 and 2013CB933401)the Chinese Academy of Sciences,China,the DFG and the state of Saxony-Anhalt,Germany
文摘A brief review is presented,which includes the direct current,alternate current,electrical and thermoelectrical transport as well as spin transfer effect in a variety of spin-based nanostructures such as the magnetic tunnel junction(MTJ),ferromagnet(FM)-quantum dot(QD)/FM-FM,double barrier MTJ,FM-marginal Fermi liquid-FM,FM-unconventional superconductor-FM(FUSF),quantum ring and optical spin-field-effect transistor.The magnetoresistances in those structures,spin accumulation effect in FM-QD-FM and FUSF systems,spin injection and spin filter into semiconductor,spin transfer effect,photon-assisted spin transport,magnonassisted tunneling,electron-electron interaction effect on spin transport,laser-controlled spin dynamics,and thermoelectrical spin transport are discussed.
基金the European Research Council(ERC)Project SPINNER,Swedish Research Council(VR Starting Grants 2016-03278,2017-05030,as well as project grant 2021-03675)Stiftelsen Olle Engkvist Byggmästare(No.200-0602)+2 种基金Energimyndigheten(No.48698-1)Formas(No.2019-01326)Wenner-Gren Stiftelserna(Nos.UPD2018-0003 and UPD2019-0166).
文摘Understanding the stability and current-carrying capacity of graphene spintronic devices is key to their applications in graphene channel-based spin current sensors,spin-torque oscillators,and potential spin-integrated circuits.However,despite the demonstrated high current densities in exfoliated graphene,the current-carrying capacity of large-scale chemical vapor deposited(CVD)graphene is not established.Particularly,the grainy nature of chemical vapor deposited graphene and the presence of a tunnel barrier in CVD graphene spin devices pose questions about the stability of high current electrical spin injection.In this work,we observe that despite structural imperfections,CVD graphene sustains remarkably highest currents of 5.2×10^(8)A/cm^(2),up to two orders higher than previously reported values in multilayer CVD graphene,with the capacity primarily dependent upon the sheet resistance of graphene.Furthermore,we notice a reversible regime,up to which CVD graphene can be operated without degradation with operating currents as high as 108 A/cm^(2),significantly high and durable over long time of operation with spin valve signals observed up to such high current densities.At the same time,the tunnel barrier resistance can be modified by the application of high currents.Our results demonstrate the robustness of large-scale CVD graphene and bring fresh insights for engineering and harnessing pure spin currents for innovative device applications.
基金supported by the National Natural Science Foundation of China(Grant No.11404322)the Natural Science Foundation of Huai’an(Grant Nos.HAB202229 and HAB202150)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(Grant No.22KJD140002)。
文摘A single-molecule magnet is a long-sought-after nanoscale component because it can enable us to miniaturize nonvolatile memory storage devices.The signature of a single-molecule magnet is switching between two bistable magnetic ground states under an external magnetic field.Based on this feature,we theoretically investigate a magnetic-fieldcontrolled reversible resistance change active at low temperatures in a molecular magnetic tunnel junction,which consists of a single-molecule magnet sandwiched between a ferromagnetic electrode and a normal metal electrode.Our numerical results demonstrate that the molecular magnetism orientation can be manipulated by magnetic fields to be parallel/antiparallel to the ferromagnetic electrode magnetization.Moreover,different magnetic configurations can be“read out”based on different resistance states or different spin polarization parameters in the current spectrum,even in the absence of a magnetic field.Such an external magnetic field-controlled resistance state switching effect is similar to that in traditional spin valve devices.The difference between the two systems is that one of the ferromagnetic layers in the original device has been replaced by a magnetic molecule.This proposed scheme provides the possibility of better control of the spin freedom of electrons in molecular electrical devices,with potential applications in future high-density nonvolatile memory devices.
基金supported by the National Natural Sci-ence Foundation of China(91750101,21733001,52072168,51861145201)the National Key Basic Research Program of the Ministry of Science and Technology of China(2018YFA0306200,2021YFA1202901)+1 种基金the Fundamental Research Funds for the Central Universities(021314380078,021314380104,021314380147)Jiangsu Key Laboratory of Artificial Functional Materials.
文摘Magnetic tunnel junctions(MTJs),a prominent type of spintronic device based on the spin valve effect,have facilitated the development of numerous spintronic applications.The technical appeal for the next-generation MTJ devices has been proposed in two directions:improving device performance by utilizing advanced two-dimensional(2D)ferromagnetic materials or extending device functionalities by exploring the gate-tunable magnetic properties of ferromagnets.Based on the recent development of 2D magnets with the ease of external stimuli,such as electric field,due to their reduced dimensions,reliable prospects for gate-tunable MTJ devices can be achieved,shedding light on the great potential of next-generation MTJs with multiple functionalities for various application environments.While the electrical gate-tunable MTJ device is highly desirable for practical spintronic devices,it has not yet been demonstrated.Here,we demonstrate the experimental realization of a spin valve device by combining a vertical Fe_(3)GeTe_(2)/h-BN/Fe_(3)GeTe_(2) MTJ with an electrolyte gate.The magnetoresistance ratio(MR ratio)of 36%for the intrinsic MTJ confirms the good performance of the device.By electrolyte gating,the tunneling MR ratio of Fe_(3)GeTe_(2)/h-BN/Fe_(3)GeTe_(2) MTJ can be elevated 2.5 times,from 26%to 65%.Importantly,the magnetic fields at which the magnetoresistance switches for the MTJ can be modulated by electrical gating,providing a promising method to control the magnetization configuration of the MTJ.Our work demonstrates a gate-tunable MTJ device toward the possibility for gate-controlled spintronic devices,paving the way for performing 2D magnetism manipulations and exploring innovative spintronic applications.
