First Principles Calculation of Dzyaloshinskii-Moriya Interaction: A Green's function Approach

TL;DR

This paper introduces a Green's function method for calculating Dzyaloshinskii-Moriya interactions from first principles, offering improved efficiency and accuracy over traditional approaches, and explores strain effects on DMI in Co/Pt bilayers.

Contribution

The paper develops a novel Green's function approach for first-principles DMI calculation, demonstrating its advantages and applying it to Co/Pt bilayers with strain analysis.

Findings

Calculated DMI values agree with experimental data.

Strain significantly modulates isotropic N{é}el DMI.

Anisotropic strains induce anisotropic DMI components.

Abstract

We present a Greens function approach to calculate the Dzyaloshinskii-Moriya interactions (DMI) from first principles electronic structure calculations, that is computationally more efficient and accurate than the most-commonly employed supercell and generalized Bloch-based approaches. The method is applied to the (111) Co/Pt bilayer where the Co- and/or Pt-thickness dependence of the DMI coefficients are calculated. Overall, the calculated DMI are in relatively good agreement with the corresponding values reported experimentally. Furthermore, we investigate the effect of strain in the DMI tensor elements and show that the isotropic N\'{e}el DMI can be significantly modulated by the normal strains, $\epsilon_{xx},\epsilon_{yy}$ and is relatively insensitive to the shear strain, $\epsilon_{xy}$. Moreover, we show that anisotropic strains, $(\epsilon_{xx}-\epsilon_{yy})$ and $\epsilon_{xy}$, result in the emergence of anisotropic N\'{e}el- and Bloch-type DMIs, respectively.