title: Consistency in formulation of spin current and torque associated with a variance of angular momentum.
abstract: Based on the Noether's theorem, we develop systematically and rigorously the spin-dependent formulation of the conservation laws. The effect of the electronic polarization due to the spin-orbit coupling is included in the Maxwell equations. The polarization is related to the antisymmetric components of spin current, and it provides a possibility to measure the spin current directly. The variances of spin and orbit angular momentum currents imply a torque on the "electric dipole" associated with the moving electron. The dependencies of the torque on the polarization and the force on the motions of spin-polarized electrons in a two-dimensional electron gas with the Rashba spin-orbit coupling are discussed.
authors.affiliation: Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.forename: Ke
authors.initials: K
authors.lastname: Xia
authors.forename: Zhao-Bin
authors.initials: ZB
authors.lastname: Su
authors.forename: Zhongshui
authors.initials: Z
authors.lastname: Ma