Manipulating magnetoelectric effect -- Essence learned from Co$_4$Nb$_2$O$_9$

TL;DR

This paper presents a minimal three-orbital model with atomic spin-orbit coupling on a honeycomb lattice that reproduces the experimentally observed manipulation of electric polarization by in-plane rotating magnetic fields in Co$_4$Nb$_2$O$_9$, shedding light on the magnetoelectric effect.

Contribution

The study introduces a minimal theoretical model capturing the magnetoelectric response in Co$_4$Nb$_2$O$_9$, explaining the electric polarization manipulation through atomic spin-orbit coupling effects.

Findings

Qualitative reproduction of the field-angle dependence of electric polarization.

Perturbative understanding of the magnetoelectric response via atomic SOC.

Potential to guide exploration of similar ME materials.

Abstract

Recent experiments for linear magnetoelectric (ME) response in honeycomb antiferromagnet Co$_4$Nb$_2$O$_9$ revealed that the electric polarization can be manipulated by the in-plane rotating magnetic field in a systematic way. We propose the minimal model by extracting essential ingredients of Co$_4$Nb$_2$O$_9$ to exhibit such ME response. It is the three-orbital model with $xy$-type atomic spin-orbit coupling (SOC) on the single-layer honeycomb structure, and it is shown to reproduce qualitatively the observed field-angle dependence of the electric polarization. The obtained results can be understood by the perturbative calculation with respect to the atomic SOC. These findings could be useful to explore further ME materials having similar manipulability of the electric polarization.