paper

Asymmetric and symmetric exchange in a generalized 2D Rashba ferromagnet

arXiv:1804.03739 · doi:10.1103/PhysRevLett.121.086802

Abstract

Dzyaloshinskii-Moriya interaction (DMI) is investigated in a 2D ferromagnet (FM) with spin-orbit interaction of Rashba type at finite temperatures. The FM is described in the continuum limit by an effective - model with arbitrary dependence of spin-orbit coupling (SOC) and kinetic energy of itinerant electrons on the absolute value of momentum. In the limit of weak SOC, we derive a general expression for the DMI constant from a microscopic analysis of the electronic grand potential. We compare with the exchange stiffness and show that, to the leading order in small SOC strength , the conventional relation , in general, does not hold beyond the Bychkov-Rashba model. Moreover, in this model, both and vanish at zero temperature in the metal regime (i.e., when two spin sub-bands are partly occupied). For nonparabolic bands or nonlinear Rashba coupling, these coefficients are finite and acquire a nontrivial dependence on the chemical potential that demonstrates the possibility to control the size and chirality of magnetic textures by adjusting a gate voltage.

6 pages, 3 figures + 2 page supplementary information; v2 corresponds to the journal version; in v3 an unfortunate mistake was corrected (in Eq.11, Im got replaced by Re)

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