The effect of spin-orbit coupling on the effective-spin correlation in YbMgGaO4

TL;DR

This paper investigates how strong spin-orbit coupling influences the effective-spin correlations in YbMgGaO4, revealing anisotropic interactions that match experimental spin-wave data and enhance correlations at specific Brillouin zone points.

Contribution

It demonstrates that anisotropic effective-spin interactions from spin-orbit coupling are sufficient to explain experimental observations in YbMgGaO4.

Findings

Anisotropic interactions reproduce spin-wave dispersion.

Spin-orbit coupling enhances correlations at M points.

Strong evidence for anisotropic interactions in YbMgGaO4.

Abstract

Motivated by the recent experiments on the triangular lattice spin liquid YbMgGaO$_4$, we explore the effect of spin-orbit coupling on the effective-spin correlation of the Yb local moments. We point out the anisotropic interaction between the effective-spins on the nearest neighbor bonds is sufficient to reproduce the spin-wave dispersion of the fully polarized state in the presence of strong magnetic field normal to the triangular plane. We further evaluate the effective-spin correlation within the mean-field spherical approximation. We explicitly demonstrate that, the nearest-neighbor anisotropic effective-spin interaction, originating from the strong spin-orbit coupling, enhances the effective-spin correlation at the M points in the Brillouin zone. We identify these results as the strong evidence for the anisotropic interaction and the strong spin-orbit coupling in YbMgGaO$_4$.