First-order multi-k phase transitions and magnetoelectric effects in multiferroic Co3TeO6

TL;DR

This paper presents a theoretical analysis of magnetic phase transitions in Co3TeO6, highlighting the first-order nature of the transition, magnetoelectric effects, and experimental verification of weak ferromagnetic domains.

Contribution

It introduces a theoretical framework explaining the first-order multiferroic phase transition and magnetoelectric effects in Co3TeO6, supported by experimental SHG measurements.

Findings

First-order transition to multiferroic ground state

Coupled order parameters induce large magnetoelastic effects

Experimental evidence of weakly ferromagnetic domains

Abstract

A theoretical description of the sequence of magnetic phases in Co3TeO6 is presented. The strongly first-order character of the transition to the commensurate multiferroic ground state, induced by coupled order parameters corresponding to different wavevectors, is related to a large magnetoelastic effect with an exchange energy critically sensitive to the interatomic spacing. The monoclinic magnetic symmetry C2' of the multiferroic phase permits spontaneous polarization and magnetization as well as the linear magnetoelectric effect. The existence of weakly ferromagnetic domains is verified experimentally by second harmonic generation measurements.