Orientation Dependence of the Critical Magnetic Field for Multiferroic BiFeO$_3$

TL;DR

This paper investigates how the critical magnetic field for phase transition in multiferroic BiFeO3 varies with the orientation of the applied magnetic field, revealing complex dependence influenced by magnetic domain competition.

Contribution

It provides a detailed analysis of the orientation dependence of the critical magnetic field in BiFeO3, including the effects of magnetic domain competition, which was not considered in earlier studies.

Findings

H_c(m) peaks along cubic diagonals parallel to P

H_c varies by up to 2.5 T from measured value

Complex dependence of H_c(m) due to domain competition

Abstract

Multiferroic BiFeO3 undergoes a transition from a distorted spiral phase to a G-type antiferromagnet above a critical field H_c that depends on the orientation m of the field. We show that H_c(m) has a maximum when oriented along a cubic diagonal parallel to the electric polarization P and a minimum in the equatorial plane normal to P when two magnetic domains with the highest critical fields are degenerate. The measured critical field along a cubic axis is about 19 T but H_c is predicted to vary by as much as 2.5 T above and below this value. The orientational dependence of H_c(m) is more complex than indicated by earlier work, which did not consider the competition between magnetic domains.