# Successive field-induced transitions in BiFeO$_{3}$ around room temperature

## TL;DR

This study investigates magnetic field-induced phase transitions in BiFeO3 near room temperature, revealing lattice distortions, an intermediate phase with strong magnetoelectric effects, and a transition from cycloidal to canted antiferromagnetic states.

## Contribution

It provides new experimental evidence and theoretical insights into successive magnetic phase transitions and intermediate states in BiFeO3 under high magnetic fields.

## Key findings

- Lattice distortion of 2×10^{-5} during spin reorientation
- Identification of an intermediate phase with large magnetoelectric effect
- Incommensurate spin modulation becomes commensurate in the intermediate phase

## Abstract

The effects of high magnetic fields applied perpendicular to the spontaneous ferroelectric polarization on single crystals of BiFeO$_3$ were investigated through magnetization, magnetostriction, and neutron diffraction measurements. The magnetostriction measurements revealed lattice distortion of $2\times 10^{-5}$, during the reorientation process of the cycloidal spin order by applied magnetic fields. Furthermore, anomalous changes in magnetostriction and electric polarization at a larger field demonstrate an intermediate phase between cycloidal and canted antiferromagnetic states, where a large magnetoelectric effect was observed. Neutron diffraction measurements clarified that incommensurate spin modulation along [110] direction in the cycloidal phase becomes commensurate in the intermediate phase. Theoretical calculations based on the standard spin Hamiltonian of this material suggest an antiferromagnetic cone-type spin order in the intermediate phase.