Antiferroelectric resonance in noncentrosymmetric multi-sublattice magnets

TL;DR

This paper predicts and develops a theory for antiferroelectric resonance (AFER), where ac electric fields induce magnetic transitions in noncentrosymmetric multi-sublattice magnets, revealing new magnetoelectric interactions and potential resonant effects.

Contribution

It introduces the concept of AFER in multi-sublattice magnets and provides a theoretical framework explaining its mechanisms and effects, including exchange enhancement and magnetooptical phenomena.

Findings

AFER occurs due to relativistic and exchange-relativistic interactions in collinear magnets.

In noncollinear magnets, exchange magnetoelectric interactions significantly contribute to AFER.

Resonant enhancement of magnetooptical effects is predicted due to AFER.

Abstract

We predict the phenomenon of antiferroelectric resonance (AFER), in which an ac electric field causes magnetic ions located at noncentrosymmetric positions in a multi-sublattice magnet to undergo magnetic transitions corresponding to exchange collective excitations of the system. We construct a theory of such resonances, and show that in magnets with collinear magnetic structures AFER is caused by relativistic and exchange-relativistic magnetoelectric interactions, while in the noncollinear magnets a significant contribution can also come from the exchange magnetoelectric interaction. We predict an exchange enhancement of the resonance by exchange modes, and discuss the role of AFER in causing resonant enhancement of magnetooptical phenomena. The main results of our theory are illustrated with the four-sublattice rhombohedral antiferromagnets {\alpha}-Fe_2O_3 and Cr_2O_3, as examples.