Nanomagnet coupled to quantum spin Hall edge: An adiabatic quantum motor
Abstract
The precessing magnetization of a magnetic islands coupled to a quantum spin Hall edge pumps charge along the edge. Conversely, a bias voltage applied to the edge makes the magnetization precess. We point out that this device realizes an adiabatic quantum motor and discuss the efficiency of its operation based on a scattering matrix approach akin to Landauer-B"uttiker theory. Scattering theory provides a microscopic derivation of the Landau-Lifshitz-Gilbert equation for the magnetization dynamics of the device, including spin-transfer torque, Gilbert damping, and Langevin torque. We find that the device can be viewed as a Thouless motor, attaining unit efficiency when the chemical potential of the edge states falls into the magnetization-induced gap. For more general parameters, we characterize the device by means of a figure of merit analogous to the ZT value in thermoelectrics.
Keywords
Cite
@article{arxiv.1507.06505,
title = {Nanomagnet coupled to quantum spin Hall edge: An adiabatic quantum motor},
author = {Liliana Arrachea and Felix von Oppen},
journal= {arXiv preprint arXiv:1507.06505},
year = {2015}
}
Comments
9 pages, 2 figures. Contribution to a special issue in Physica E on "Frontiers in quantum electronic transport" - in memory of Markus B"uttiker