Conserved spin current with a perpendicular magnetic field |
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Institution: | Department of Physics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan |
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Abstract: | Previous theoretical studies show that the spin current in spin-orbit coupled systems can be effectively conserved. In this study, we show that in the presence of an external magnetic field B perpendicular to the surface without causing Landau levels, the spin-Hall conductivity, including the conventional spin and spin-torque Hall currents exhibit an interesting symmetry, valid for k-linear and k-cubic Rashba systems. The phenomenon where the electric field generated spin z component is unaltered under is attributed to the fact that the spin precession is locked in spin-orbit coupled systems. The perpendicular magnetic field generates spin x and y components, which are linear to B, and thus, there is no time-reversal symmetry. This result provides evidence for the detection of the bulk spin-Hall current. Furthermore, the applied magnetic field breaks the degenerate point of the two-band model, and the resulting spin-Hall conductivity does not vanish even for systems with linear momentum, which implies that the Berry phase is not the principal mechanism in k-linear systems. The non-zero charge-Hall conductivity generated by the perpendicular magnetic field is discussed here. |
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Keywords: | Spin-orbit coupling Conserved spin current Spin torque current Rashba system |
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