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Magnetic Field Effects on Quantum-Dot Spin Valves

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Communications in Theoretical Physics 2009年第3期51卷 555-562页

作者： GAO Jin-Hua,~1 SUN Qing-Feng,~1 and XIE Xin-Cheng~(1,2)1 Beijing National Lab for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences,Beijing 100080, China2 Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078, USA Beijing National Lab for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences Beijing 100080 China Department of Physics Oklahoma State University Stillwater Oklahoma 74078 USA

We study the magnetic field effects on the spin-polarized transport of the quantum dot (QD) spin valve inthe sequential tunneling regime. A set of generalized master equation is derived. Based on that, we discuss the collinearand noncollinear magnetic field effects, respectively. In the collinear magnetic field case, we find that the Zeeman splittingcan induce a negative differential conductance (NDC), which is quite different from the one found in previous *** has a critical polarization in the parallel arrangement and will disappear in the antiparallel configuration. In thenoncollinear magnetic field case, the current shows two plateaus and their angular dependence is analyzed. Althoughsometimes the two current plateaus have similar angular dependence, their mechanisms are different. Our formalism isalso suitable for calculating the transport in magnetic molecules, in which the spin splitting is induced not by a magneticGeld but by the intrinsic magnetization.

关键词： spin value spintronics quantum dot

Controllable Spin-Polarized Transport in a Three-Terminal Model

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Communications in Theoretical Physics 2012年第6期57卷 1081-1086页

作者：梁峰杨永宏汪军 Department of Physics Huaiyin Institute of Technology Department of Physics Southeast University

By means of the Keldysh Green's function method,we investigate the spin-polarized electron transport in a three-terminal device,which is composed of three normal metal leads and two serially-coupled quantum dots(QDs).The Rashba spin-orbit interaction(RSOI) is also considered in one of the *** show that the spin-polarized charge current with arbitrary spin polarization can be obtained because of the quantum spin interference effect arising from the Rashba spin precession phase,and it can be modulated by the system parameters such as the applied external voltages,the RSOI strength,the QD levels,as well as the dot-lead coupling ***,a fully spin-polarized current or a pure spin current without any accompanying charge current can also be controlled to flow in the *** findings indicate that the proposed model can serve as an all-electrical spin device in spintronics field.

关键词： spintronics spin current Rashba spin-orbit interaction quantum dot Keldysh Green's function

Effective Mass of Strong-Coupling Bound Polaron in a Triangular Quantum Well Induced by Rashba Effect

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Communications in Theoretical Physics 2008年第10期50卷 995-998页

作者： ZHANG Hai-Rui XIAO Jing-Lin Department of Mathematics and Physics Hebei Normal University of Science and Technology Qinhuangdao 066004 China College of Physics and Electronic Information Inner Mongolia National University Tongliao 028043 China

In this paper, on the basis of Huybrechts＇ strong-coupling polaron model, the Tokuda modified linearcombination operator method and the unitary transformation method are used to study the properties of the strongcoupling bound polaron considering the influence of Rashba effect, which is brought by the spin-orbit （SO） interaction, in the semiconductor triangular quantum well （TQW）. Numerical calculation on the RbCI TQW, as the example, is performed. The expressions for the effective mass of the polaron as a function of the vibration frequency, the velocity, the Coulomb bound potential and the electron areal density are derived. Numerical results show that the total effective mass of the polaron is composed of three parts. The interactions between the orbit and the spin with different directions have different effects on the effective mass of the bound polaron.

关键词： triangular quantum well spintronics effective mass Rashba SO interaction

Spin manipulations through electrical and thermoelectrical transport in magnetic tunnel junctions

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Science China(Physics,Mechanics & Astronomy) 2013年第1期56卷 166-183页

作者： ZHU ZhenGang SU Gang School of Electronics Eletrical and Communication EngineeringUniversity of Chinese Academy of Sciences Institut fr Physik Martin-Luther-UniversittHalle-Wittenberg Nanotechnikum-WeinbergHeinrich-Damerow-Strasse 4 D-06120 Halle(Saale)Germany School of Physics University of Chinese Academy of Sciences

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 *** 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.

关键词： spintronics magnetic tunnel junction spin transport magnetoresistance spin transfer torque spin injection spin filter spin-valve spin-orbit

Spintronic materials and devices based on antiferromagnetic metals

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Progress in Natural Science:Materials International 2017年第2期27卷 208-216页

作者： Yuyan Wang Cheng Song Junying Zhang Feng Pan Department of Physics Beihang University Key Laboratory of Advanced Materials (MOE) School of Materials Science and EngineeringTsinghua University

In this paper, we review our recent experimental developments on antiferromagnet(AFM) spintronics mainly comprising Mn-based noncollinear AFM metals. Ir Mn-based tunnel junctions and Hall devices have been investigated to explore the manipulation of AFM moments by magnetic fields, ferromagnetic materials and electric fields. Room-temperature tunneling anisotropic magnetoresistance based on Ir Mn as well as Fe Mn has been successfully achieved, and electrical control of the AFM exchange spring is realized by adopting ionic liquid. In addition, promising spin-orbit effects in AFM as well as spin transfer via AFM spin waves reported by different groups have also been reviewed, indicating that the AFM can serve as an efficient spin current *** explore the crucial role of AFM acting as efficient generators, transmitters, and detectors of spin currents is an emerging topic in the field of magnetism today. AFM metals are now ready to join the rapidly developing fields of basic and applied spintronics, enriching this area of solid-state physics and microelectronics.

关键词： Antiferromagnetic metals spintronics Tunneling anisotropic magnetoresistance Electrical manipulation

Electric field induced magnetization reversal in magnet/insulator nanoheterostructure

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International Journal of Smart and Nano Materials 2020年第3期11卷 298-309页

作者： Qihua Gong Min Yi Bai-Xiang Xu Institute of Materials Science Technische Universität DarmstadtDarmstadtGermany State Key Lab of Mechanics and Control of Mechanical Structures&Key Lab for Intelligent Nano Materials and Devices of Ministry of Education&College of Aerospace Engineering Nanjing University of Aeronautics and Astronautics(NUAA)NanjingChina

Electric-field control of magnetization reversal is promising for lowpower *** in a magnet/insulator nanoheterostructure which is the fundamental unit of magnetic tunneling junction in spintronics,we demonstrate the electric field induced 180°magne-tization switching through a multiscale study combining firstprinciples calculations and finite-temperature magnetization *** the model nanoheterostructure MgO/Fe/Cu with insu-lator MgO,soft nanomagnet Fe and capping layer Cu,through firstprinciples calculations we find its magnetocrystalline anisotropy linearly varying with the electric *** finite-temperature magnetization dynamics which is informed by the first-principles results,we disclose that a room-temperature 180°magnetization switching with switching probability higher than 90%is achievable by controlling the electric-field pulse and the nanoheterostructure *** 180°switching could be fast realized within 5 *** study is useful for the design of low-power,fast,and miniaturized nanoscale electric-field-controlled spintronics.

关键词： Magnetization reversal nanoheterostructure electric field spintronics multiscale simulations switching probability

Energy-resolved spin filtering effect and thermoelectric effect in topological-insulator junctions with anisotropic chiral edge states

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Frontiers of physics 2022年第6期17卷 85-93页

作者： Jia-En Yang Hang Xie School of Electronics and IoT Chongqing College of Electronic EngineeringChongqing 401331China College of Physics Chongqing UniversityChongqing 401331China Chongqing Key Laboratory for Strongly-Coupled Physics Chongqing UniversityChongqing 401331China

Topological edge states have crucial applications in the future nano spintronics *** this work,circularly polarized light is applied on the zigzag silicene-like nanoribbons resulting in the anisotropic chiral edge *** energy-dependent spin filter is designed based on the topological-insulator(TI)junctions with anisotropic chiral edge *** resonance transmission has been observed in the TI junctions by calculating the local current *** some strong Fabry–Perot resonances are found leading to the sharp transmission ***,the weak and asymmetric resonance corresponds to the broad transmission *** addition,a qualitative relation between the resonant energy separation TR and group velocity vf is derived:TR=πhvf n/L,that indicated TR is proportional to vf and inversely proportional to the length L of the *** different TR between the spin-up and spin-down cases results in the energyresolved spin filtering ***,the intensity of the circularly polarized light can modulate the group velocity ***,the intensity of circularly polarized light,as well as the conductor-length,play very vital roles in designing the energy-dependent spin *** the transmission gap root in the Fabry–Perot resonances,the thermoelectric(TE)property can be enhanced by adjusting the gap.A schedule to enhance the TE performance in the TI-junction is proposed by modulating the electric field(Ez).The TE dependence on Ez in the nanojunction is investigated,where the appropriate Ez leads to a very high spin thermopower and spin figure of *** TI junctions have potential usages in the nano spintronics and thermoelectric devices.

关键词： electron transport topological edge states 2D materials spintronics thermoelectric effects

Monte-Carlo simulation studies of the effect of temperature and diameter variation on spin transport in Ⅱ–Ⅵ semiconductor nanowires

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Journal of Semiconductors 2015年第2期36卷 1-1,2-5页

作者： Sabiq Chishti Bahniman Ghosh Bhupesh Bishnoi Department of Electrical Engineering Indian Institute of Technology Kanpur Microelectronics Research Center 10100 Burnet Road University of Texas at Austin

We have analyzed the spin transport behaviour of four II-VI semiconductor nanowires by simulating spin polarized transport using a semi-classical Monte-Carlo approach. The different scattering mechanisms con- sidered are acoustic phonon scattering, surface roughness scattering, polar optical phonon scattering, and spin flip scattering. The II-VI materials used in our study are CdS, CdSe, ZnO and ZnS. The spin transport behaviour is first studied by varying the temperature （4-500 K） at a fixed diameter of 10 nm and also by varying the diameter （8-12 nm） at a fixed temperature of 300 K. For II-VI compounds, the dominant mechanism is for spin relaxation; D＇yakonovPerel and Elliot Yafet have been actively employed in the first order model to simulate the spin transport. The dependence of the spin relaxation length （SRL） on the diameter and temperature has been analyzed.

关键词： spintronics spin transport II-VI nanowire spin relaxation lengths Monte Carlo method

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Chinese Chemical Letters 2023年第1期34卷 203-205页

作者： Mingjun Zhong Qimeng Wu Liang Ma Jie Li Yifan Wang Yansong Wang Xin Li Yajie Zhang Jingtao Lü Yongfeng Wang Center for Carbon-based Electronics and Key Laboratory for the Physics and Chemistry of Nanodevices Department of ElectronicsPeking UniversityBeijing 100871China Key Laboratory for Microstructural Material Physics of Hebei Province School of ScienceYanshan UniversityQinhuangdao 066004China School of Physics Institute for Quantum Science and Engineeringand Wuhan National High Magnetic Field CenterHuazhong University of Science and TechnologyWuhan 430074China Beijing Academy of Quantum Information Sciences Beijing 100193China Institute of Spin Science and Technology South China University of TechnologyGuangzhou 511442China

Spin properties of organic molecules have attracted great interest for their potential applications in spintronic devices and quantum ***-tetraphenyl porphyrin(Fe TPP)is of particular interest for its robust magnetic properties on metallic *** TPP is prepared in vacuum via on-surface *** structure and spin-related transport properties are characterized by low-temperature scanning tunneling microscope and spectroscopy at 0.5 *** functional theory calculations are performed to understand molecular adsorption and spin distribution on Au(111).The molecular structure of Fe TPP is distorted upon adsorption on the *** excitations of Fe TPP are observed on the Fe atom and high pyrrole groups in differential conductance *** calculated spin density distribution indicates that the electron spin of Fe TPP is mainly distributed on the Fe *** atomic transmission calculation indicates that electrons transport to substrate is mediated through Fe atom,when the tip is above the high pyrrole group.

关键词： spintronics Spin excitation Atomic transmission Fe-tetraphenyl porphyrin STM