Persistent spin current in a quantum wire with weak Dresselhaus spin——orbit coupling

The spin current in a parabolically confined semiconductor heterojunction quantum wire with Dresselhaus spin--orbit coupling is theoretically studied by using the perturbation method. The formulae of the elements for linear and angular spin current densities are derived by using the recent definition for spin current based on spin continuity equation. It is found that the spin current in this Dresselhaus spin--orbit coupling quantum wire is antisymmetrical, which is different from that in Rashba model due to the difference in symmetry between these two models. Some numerical examples for the result are also demonstrated and discussed.     

极端条件下的核结构

本文评述了原子核结构研究的新进展和面临的新挑战．指出当今原子核结构发展方向的基本特点是“极端条件下的核结构”,它的主要内容是高自旋态物理和远离稳定线直至滴线原子核两个方面．而这些新发展方向,有新一代超级γ谱探测器系统和放射性核束加速器的发展和建造做为坚实的技术保证． This paper reviews the new developments and new challenges for the nuclear structure studies. It points out that the developments of the nuclear structure today is characterized by the term u Nuclear Structure in Exotic Conditions",the main contents of which are the high spin physics and physics for the nuclei far from the stability line and up to drip lines.All these new developments are solidly ensured by the developments and the constructions of super γ- ray spe ctrometer...     

Spin-Dependent Transport and Densities of States in Non-collinear Magnetic Barriers

The spin-dependent transport properties in the non-collinear pattern of series of δ-magnetic barriers are studied by using scattering theory and Green＇s function methods. The Green＇s function is obtained by using distorted wave approach and the scattering matrix is related by Fisher-Lee relationship. In addition to reproducing the results of Papp＇s and Xu＇s in parallel and antiparallel configurations, we also obtain further results, where arbitrary orientations of the magnetic barriers and arbitrary number of barriers are included. The main finding of our results is that the signs of polarizations can be switched around some ＂geometric unpolarized windows＂. The well-known antiparallel configuration has no such characteristics. Furthermore, we discuss spin-related partial densities of states in both polarized and unpolarized structures.     

液晶光阀的偏光显示特性分析

讨论了液晶光阀的偏光扭曲向列性效应, 分析了液晶光阀中液晶分子在交流电场作用下重新取向后的扭曲, 测量了TB3639型液晶光阀在特定的频率连续改变外加交流电压条件下,液晶分子重新取向后的扭曲角度以及液晶光阀的电光特性。测量结果表明,在外加电压连续改变时,入射线偏振光的透射率呈现连续非线性变化,这种非线性变化可以由液晶分子的扭曲量来改变。同时液晶分子180°的扭曲使得液晶光阀具有较陡的电光特性曲线,这对于多通道矩阵寻址方式的液晶光阀而言在矩阵显示中可有更多的通道寻址线和更高的对比度。     

Influence of Rashba SOI and Polaronic Effects on the Ground-State Energy of Electrons in Semiconductor Quantum Rings

The influence of Rashba spin-orbit interaction （SOI） and polaronic effect on the ground-state energy of electrons in semiconductor quantum rings （QRs） are studied by means of the Lee-Low-Pines variational method. Numerical calculations for GaAs QRs are performed and the results show that the ground-state energy of electrons splits into two branches as E（↑） and E（↓） under the Rashba SOI, which correspond to the spin-up state and spin-down state, respectively. The contribution of the Rashba SOI effect to the ground-state energy of electrons is related to the spin state of electrons and is closely linked to the inner and outer radii of a QR. However, it is independent of the height of the QR. The ground-state energy of electrons decreases due to the polaronic effect in QRs. The energy shift ＆#8710;Ee-LO of the ground-state of the electron induced by the polaronic effect decreases monotonically with increase of the height of a QR and fluctuates with the changes of the radii of QRs. The amplitude of the fluctuation is very sensitive and remarkable to the changes of the inner radius R1 and the outer radius R2.     

光格中玻色-爱因斯坦凝聚的自旋磁子和自旋波北大核心CSCD

研究了一维光格中旋量玻色—爱因斯坦凝聚体的自旋磁子和自旋波.求出了自旋磁子和自发磁化强度.用经典方法求得了均匀体系的自旋波和能级以及激光调制下的自旋波和能级.特别是在连续极限近似下,求得了马丢函数波及其能级.     

Effects of oxygen vacancy location on the electronic structure and spin density of Co-doped rutile TiO2 dilute magnetic semiconductors

According to density functional theory （DFT） using the plane wave base and pseudo-potential, we investigate the effects of the specific location of oxygen vacancy （Vo） in a （Ti,Co）06 distorted octahedron on the spin density and magnetic properties of Co-doped rutile Ti02 dilute magnetic semiconductors. Our calculations suggest that the Vo location has a significant influence on the magnetic moment of individual Co cations. In the case where two Co atoms are separated far away from each other, when the Vo is located at the equatorial site of a Co-contained octahedron, the ground state of the two Co cations is d6（t3g↑, t23g ↓） without any magnetic moment. However, if the Vo is located at the apical site, these two Co sites have different ground states and magnetic moments. The spin densities are also observed to be modified by the exchange coupling between the Co cations and the location of Vo. Some positive spin polarization is induced around the adjacent O ions.     

自旋阀与多层膜巨磁电阻的特性测量及比较

介绍磁性多层膜中自旋极化输运和巨磁电阻效应,简述自旋阀巨磁电阻与多层膜巨磁电阻在材料组成结构和工作原理方面的区别,利用和改造现有的高校物理实验室中的实验仪器并设计简易的实验电路测量这两种类型的巨磁电阻的磁敏特性,并根据实验测量的结果将这两种传感器在其灵敏度和测量范围上进行比较和研究.     

应力调制的自旋转矩临界电流

自旋转矩临界电流过大的问题长期以来一直为人们所关注.本文提出,可以通过引入面外应力即引入应力各向异性场来降低退磁场,从而降低自旋转矩的临界电流.本文采用四分量分布式自旋电路模型计算了横向自旋阀由注入端输运到探测端(自由层)的极化电流大小.利用Landau-Lifshitz-Gilbert-Slonczewski方程数值研究了存在应力时,横向自旋阀中自旋转矩引起的自由层磁矩翻转的性质.结果表明,适当选择应力方向可使面外退磁场得到有效补偿,从而显著降低自旋转矩临界电流.另外,随着应力提高和退磁场的减小,磁矩翻转时间也大大减小.     

EAST装置内置低温冷凝泵低温分配阀箱的研制

在全超导磁约束核聚变试验装置EAST中,为了防止杂质从偏虑器靶板附近进入等离子体核心,为EAST长脉冲放电试验提供持续的排灰能力以及装置长冲放电等,低温冷凝泵是必不可少的部件之一,在装置真空室上下安装了内置低温凝泵以提高装置运行参数,为满足低温泵的低温条件,增加一低温分配阀箱给内置低温冷凝泵提供低温条件。文中介绍应用于EAST装置系统中的内置低温冷凝泵分配阀箱研制的技术要求、冷却流程、结构特征。