Thermal generation of magnetization via orbital degree of freedom in low-symmetry two dimensional systems

Cong Xiao, Qian Niu

Published 2020-02-05Version 1

We propose an orbital magnetothermal effect wherein the temperature gradient generates an out-of-plane orbital magnetization of Bloch electrons in low-symmetry two-dimensional (2D) systems. We provide the hitherto absent theoretical approach to attaining the linear thermoelectric responses of the orbital magnetization, which does not correspond to a single-particle operator in extended-state systems thus is hard to fit into the linear response theory. The Mott relation is extended to such thermoelectric responses. The different symmetry requirements and temperature dependencies of intrinsic and extrinsic responses are elucidated. Besides, we propose a phonon-drag orbital magnetization and point out the presence of a peak in its temperature dependence. These results are relevant to various 2D systems with reduced symmetry, opening the door to thermal generation and control of magnetization via the orbital degree of freedom.