Ab Initio Cycloidal and Chiral Magnetoelectric Responses in Cr$_{2}$O$_{3}$

TL;DR

This study uses density functional theory to analyze the magnetoelectric effect in Cr₂O₃, revealing distinct relativistic cycloidal and chiral responses in different magnetic phases.

Contribution

It provides a detailed ab initio analysis of the magnetoelectric tensor in Cr₂O₃, identifying multiple components including relativistic cycloidal and chiral contributions.

Findings

Identified three components of the magnetoelectric tensor in Cr₂O₃.

Discovered a relativistic cycloidal term independent of spin orientation.

Revealed a chiral, non-toroidal ME response active in spin flop phases.

Abstract

We present a thorough density functional theory study of the magneto-electric (ME) effect in Cr$_{2}$O$_{3}$. The spin-lattice ME tensor $\alpha$ was determined in the low-field and spin flop (SF) phases, using the method of dynamical magnetic charges, and found to be the sum of three distinct components. Two of them, a large relativistic "cycloidal" term and a small longitudinal term, are independent on the spin orientation. The third, only active in the SF phases is also of relativistic origin and arises from magnetic-field-induced chirality, leading to a non-toroidal ME response.