Multiferroic phase transition near room temperature in BiFeO3 films

TL;DR

This study reports a multiferroic phase transition near room temperature in BiFeO3 films, where coupled structural, ferroelectric, and magnetic changes occur, promising for multifunctional device applications.

Contribution

It reveals the coexistence of two polymorphs in BiFeO3 films and details their coupled ferroic transitions near room temperature, a novel insight into multiferroic behavior.

Findings

Abrupt structural change at 360 K

Transition from antiferromagnetic to paramagnetic

Enhanced multiferroic responses near room temperature

Abstract

In multiferroic BiFeO3 thin films grown on highly mismatched LaAlO3 substrates, we reveal the coexistence of two differently distorted polymorphs that leads to striking features in the temperature dependence of the structural and multiferroic properties. Notably, the highly distorted phase quasi-concomitantly presents an abrupt structural change, transforms from a hard to a soft ferroelectric and transitions from antiferromagnetic to paramagnetic at 360+/-20 K. These coupled ferroic transitions just above room temperature hold promises of giant piezoelectric, magnetoelectric and piezomagnetic responses, with potential in many applications fields.