We theoretically investigate spin transport in the elliptical ring and the circular ring with Rashba spin-orbit interaction. It is shown that when Rashba spin-orbit interaction is relatively weak, a single circular ri...We theoretically investigate spin transport in the elliptical ring and the circular ring with Rashba spin-orbit interaction. It is shown that when Rashba spin-orbit interaction is relatively weak, a single circular ring can not realize spin flip, however an elliptical ring may work as a spin-inverter at this time, and the influence of the defect of the geometry is not obvious. Howerver if a giant Rashba spin-orbit interaction strength has been obtained, a circular ring can work as a spin-inverter with a high stability.展开更多
We theoretically investigate the Kondo effect of a quantum dot embedded in a mesoscopic Aharonov-Bohm(AB)ring in the presence of the spin flip processes by means of the one-impurity Anderson Hamiltonian.Based on thesl...We theoretically investigate the Kondo effect of a quantum dot embedded in a mesoscopic Aharonov-Bohm(AB)ring in the presence of the spin flip processes by means of the one-impurity Anderson Hamiltonian.Based on theslave-boson mean-field theory,we find that in this system the persistent current(PC)sensitively depends on the parityand size of the AB ring and can be tuned by the spin-flip scattering(R).In the small AB ring,the PC is suppresseddue to the enhancing R weakening the Kondo resonance.On the contrary,in the large AB ring,with R increasing,thepeak of PC firstly moves up to max-peak and then down.Especially,the PC phase shift of π appears suddenly withthe proper value of R,implying the existence of the anomalous Kondo effect in this system.Thus this system may be acandidate for quantum switch.展开更多
We investigate the spin-flip process through double quantum dots coupled to two half-metallic ferromagnetic leads in series. By means of the slave-boson mean-field approximation, we calculate the density of states in ...We investigate the spin-flip process through double quantum dots coupled to two half-metallic ferromagnetic leads in series. By means of the slave-boson mean-field approximation, we calculate the density of states in the Kondo regime for two different configurations of the leads. It is found that the transport shows some remarkable properties depending on the spin-flip strength. These effects may be useful in exploiting the role of electronic correlation in spintronics.展开更多
We theoretically studied the nonlocal Andreev reflection with Rashba spin-orbital interaction in a triple-quantumdot （QD） ring, which is introduced as Rashba spin-orbital interaction to act locally on one component ...We theoretically studied the nonlocal Andreev reflection with Rashba spin-orbital interaction in a triple-quantumdot （QD） ring, which is introduced as Rashba spin-orbital interaction to act locally on one component quantum dot. It is found that the electronic current and spin current are sensitive to the systematic parameters. The interdot spin-flip term does not play a leading role in causing electronic and spin currents. Otherwise the spin precessing terra leads to shift of the peaks of the the spin-up and spin-down electronic currents in different directions and results in the spin current. Moreover, the spin-orbital interaction suppresses the nonlocal Andreev reflection, so we cannot obtain the pure spin current.展开更多
The spin polarization phenomenon in lepton circular accelerators had been known for many years. It provides a new approach for physicists to study the spin feature of fundamental particles and the dynamics of spin-orb...The spin polarization phenomenon in lepton circular accelerators had been known for many years. It provides a new approach for physicists to study the spin feature of fundamental particles and the dynamics of spin-orbit coupling, such as spin resonances. We use numerical simulation to study the features of spin under the modulation of orbital motion in an electron storage ring. The various cases of depolarization due to spin-orbit coupling through an emitting photon and misalignment of magnets in the ring are discussed.展开更多
Spin-dependent transmission coefficients as a function of Fermi energy is calculated for electron scattering from magnetic impurity in a narrow quantum wire, in which spin-exchange interaction between conducting elect...Spin-dependent transmission coefficients as a function of Fermi energy is calculated for electron scattering from magnetic impurity in a narrow quantum wire, in which spin-exchange interaction between conducting electron and the impurity leads to exchange spin-flip scattering. Transmission in the spin-flipped channels is explicitly calculated. It has been found that spin-up and spin-down transmission coefficients for intrasubband and intersubband enhance Fano-resonance profiles, which have asymmetric behaviors, whenever Fermi energy crosses bottom of every subband below. Meanwhile due to dephasing of electron wave caused by spin-flip scattering, the entanglement between spin states of electron and magnetic impurity obviously destroys the global step structure of quantized conductance and suppresses the height of the conductance step.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.11504016)
文摘We theoretically investigate spin transport in the elliptical ring and the circular ring with Rashba spin-orbit interaction. It is shown that when Rashba spin-orbit interaction is relatively weak, a single circular ring can not realize spin flip, however an elliptical ring may work as a spin-inverter at this time, and the influence of the defect of the geometry is not obvious. Howerver if a giant Rashba spin-orbit interaction strength has been obtained, a circular ring can work as a spin-inverter with a high stability.
基金Supported by Scientific Research Fund of Hunan Provincial Education Department under Grant No.09B079
文摘We theoretically investigate the Kondo effect of a quantum dot embedded in a mesoscopic Aharonov-Bohm(AB)ring in the presence of the spin flip processes by means of the one-impurity Anderson Hamiltonian.Based on theslave-boson mean-field theory,we find that in this system the persistent current(PC)sensitively depends on the parityand size of the AB ring and can be tuned by the spin-flip scattering(R).In the small AB ring,the PC is suppresseddue to the enhancing R weakening the Kondo resonance.On the contrary,in the large AB ring,with R increasing,thepeak of PC firstly moves up to max-peak and then down.Especially,the PC phase shift of π appears suddenly withthe proper value of R,implying the existence of the anomalous Kondo effect in this system.Thus this system may be acandidate for quantum switch.
基金Project supported by Scientific Research Fund of Sichuan Provincial Education Department of China (Grant No 2006A069)Funds for Major Basic Research Project of Sichuan Province, China (Grant No 2006J13-155)
文摘We investigate the spin-flip process through double quantum dots coupled to two half-metallic ferromagnetic leads in series. By means of the slave-boson mean-field approximation, we calculate the density of states in the Kondo regime for two different configurations of the leads. It is found that the transport shows some remarkable properties depending on the spin-flip strength. These effects may be useful in exploiting the role of electronic correlation in spintronics.
基金Project supported by the Natural Science Foundation of Education Bureau of Jiangsu Province of China (Grant Nos. 08KJB140002 and 09KJD430004)
文摘We theoretically studied the nonlocal Andreev reflection with Rashba spin-orbital interaction in a triple-quantumdot （QD） ring, which is introduced as Rashba spin-orbital interaction to act locally on one component quantum dot. It is found that the electronic current and spin current are sensitive to the systematic parameters. The interdot spin-flip term does not play a leading role in causing electronic and spin currents. Otherwise the spin precessing terra leads to shift of the peaks of the the spin-up and spin-down electronic currents in different directions and results in the spin current. Moreover, the spin-orbital interaction suppresses the nonlocal Andreev reflection, so we cannot obtain the pure spin current.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10875118)
文摘The spin polarization phenomenon in lepton circular accelerators had been known for many years. It provides a new approach for physicists to study the spin feature of fundamental particles and the dynamics of spin-orbit coupling, such as spin resonances. We use numerical simulation to study the features of spin under the modulation of orbital motion in an electron storage ring. The various cases of depolarization due to spin-orbit coupling through an emitting photon and misalignment of magnets in the ring are discussed.
文摘Spin-dependent transmission coefficients as a function of Fermi energy is calculated for electron scattering from magnetic impurity in a narrow quantum wire, in which spin-exchange interaction between conducting electron and the impurity leads to exchange spin-flip scattering. Transmission in the spin-flipped channels is explicitly calculated. It has been found that spin-up and spin-down transmission coefficients for intrasubband and intersubband enhance Fano-resonance profiles, which have asymmetric behaviors, whenever Fermi energy crosses bottom of every subband below. Meanwhile due to dephasing of electron wave caused by spin-flip scattering, the entanglement between spin states of electron and magnetic impurity obviously destroys the global step structure of quantized conductance and suppresses the height of the conductance step.
基金supported by the National Natural Science Foundation of China(21002006,20452002)Special Program for Key Basic Research of the Ministry of Science and Technology,China(2004-973-36)~~
基金supported by the National Natural Science Foundation of China (21002006,20452002)Special Program for Key Basic Research of the Ministry of Science and Technology,China (2004-973-36)~~
基金supported by the National Natural Science Foundation of China(21002006,20452002)Special Program for Key Basic Research of the Ministry of Science and Technology,China(2004-973-36)~~
文摘二维快速自旋回波(Two Dimensional Turbo Spin Echo,2D TSE)是目前临床应用十分广泛的一项成像技术。通过与隔层扫描技术相结合,2D TSE已在短时间内迅速应用于整个大脑的成像。由于射频能量吸收率(Specific Absorption Rate,SAR)以及T2衰减的影响,TSE数据采集效率难以满足三维成像的要求。SPACE(Sampling Perfection with Application-optimized Contrasts by using different flip angle Evolutions)在TSE的基础上,采用非选择回聚脉冲和可变翻转角,克服了SAR和T2衰减的影响,满足了临床对三维TSE的需求。文章将详细介绍SPACE的基本原理,分析成像参数对图像质量的影响,并简单介绍SPACE在人体各个部位的临床应用及其前景展望。
