| 报告题目： |
Spin current and the features of spin Hall effects—predictions and recent developments |
| 报告人： |
李有泉教授 |
| 报告人单位： |
Department of Physics, Zhejiang University |
| 报告时间： |
2016年10月20日 周四下午3：50 |
| 报告地点： |
科技楼北410 |
| 报告摘要： |
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In terms of SU(2) Yang-Mills field formulism, we gave a natural definition of spin current for the systems with Rashba or Dresselhaus spin-orbit couplings and obtain a covariant form of continuity equations for the corresponding spin current[1]. Such a covariant form has been applied to develop scheme of spin-orbit echo recently [2]. We developed the traditional Kubo formula to describe the linear response with respect to non-Abelian fields, in which the covariant form plays an essential role in guaranteeing the consistency of SU(2) Kubo formula[3]. We also derive the classical counterpart of quantum mechanical covariant “continuity-like” equation for the spin current, and present an intuitive picture for elucidating the non-conservation of the spin current[4]. We discuss the spin-relaxation time for two-dimensional systems with a hierarchy of spin-orbit couplings, and found that the spin-relaxation time can be infinite if the coupling strengths certain condition which correspond to the vanishing Yang-Mills “magnetic” field[5]. The intrinsic spin Hall conductivity in a two dimensional electron gas with Rashba spin-orbit coupling is investigated by taking account of impurities. Our evaluation of the vertex corrections for the anisotropic magnetic impurities gives a nonvanishing spin Hall conductivity[6]. We reveal that, due to the existence of inelastic scattering which may arise from electron-electron interaction[7], the spin Hall conductivity does not vanish when the impurity concentration diminishes to zero no matter it is non-magnetically or magnetically disordered [8] that was confirmed later by experimentalists[9]. Spin transport properties of a coupled bilayer electron gas with Rashba spin-orbit coupling are studied. Our investigation on the impurity effect manifests that an arbitrarily small concentration of nonmagnetic impurities does not suppress the spin Hall conductivity to zero in the bilayer system. Based on these features, an experimental scheme is suggested to detect a magnification of the spin Hall effects[10], which has been realized in experiments recently[11,12].
[1] Pei-Qing Jin, You-Quan Li, and Fu-Chun Zhang, J. Phys. A: Math. Gen. 39 (2006) 7115-7123, online e-print was posted earlier, arXiv:cond-mat/0502231.
[2] N Sugimoto and N Nagaosa, Science 336, 1413 (2012).
[3] Pei-Qing Jin and You-Quan Li, Phys. Rev. B 74, 085315 (2006).
[4] Pei-Qing Jin and You-Quan Li, Phys. Rev. B 77, 155304 (2008).
[5] Yuan Li and You-Quan Li, J. Phys.: Condens. Matter 19, 346231 (2007).
[6] Pei Wang, You-Quan Li, and Xuean Zhao, Phys. Rev. B 75, 075326 (2007).
[7] Yuan Li and You-Quan Li, Phys. Rev. B 78, 195325 (2008).
[8] Pei Wang, You-Quan Li, J. Phys.: Condens. Matter 20, 215206 (2008).
[9] H. Noh, S.J. Lee, and S.H. Chun, J. Phys.: Condens. Matter 25, 045301 (2013).
[10] Pei-Qing Jin and You-Quan Li, Phys. Rev. B 76, 235311 (2007).
[11] M Akabori, S Hidaka et al., J. Appl. Phys. 112, 113711 (2012).
[12] F.G.G. Hernandez, L.M. Nunes, et al., Phys. Rev. B 88, 161305(R) (2013). |
| 报告人简介： |
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李有泉教授，教育部长江学者，浙江省特级专家，德国亚历山大·冯·洪堡学者。于兰州大学物理系先后获学士学位(1983)、硕士学位(1986)、博士学位(1989)。现任职于浙江大学理学院物理系浙江近代物理中心。主持完成教育部跨世纪人才基金、优秀青年基金项目、国家杰出青年基金等项目。因“轨道简并自旋系统的SU(4)理论”等工作先后获得了中国高校自然科学一等奖、国家自然科学二等奖、第八届中国青年科技奖。 |
