Epitaxially Strained BiMnO3 Films: High-Temperature Robust Multiferroic Materials with Novel Magnetoelectric Coupling

TL;DR

This study uses first principles calculations to show that epitaxial strain can stabilize a high-temperature, robust multiferroic phase in BiMnO3 films with strong magnetoelectric coupling, promising for applications.

Contribution

It demonstrates that tensile epitaxial strain induces a stable ferromagnetic and ferroelectric phase in BiMnO3 with high Curie temperature and novel magnetoelectric coupling, which was not previously known.

Findings

Epitaxial strain stabilizes ferromagnetic and ferroelectric Cc phase.

The Cc phase exhibits high polarization (>80 μC/cm2).

Predicted Curie temperature between 169 K and 395 K.

Abstract

Multiferroics with the coexistence of ferroelectric and ferromagnetic orders are ideal candidates for magnetoelectric applications. Unfortunately, only very few ferroelectric-ferromagnetic multiferroics (with low magnetic critical temperature) were discovered. Here we perform first principles calculations to investigate the effects of the epitaxial strain on the properties of BiMnO3 films grown along the pseudocubic [001] direction. Unlike the ground state with the centrosymmetric C2/c space group in bulk, we reveal that the tensile epitaxial strain stabilizes the ferromagnetic and ferroelectric Cc state with a large polarization (P > 80 {\mu}C/cm2) and high Curie temperature (Tc is predicted to be between 169 K and 395 K). More importantly, there is a novel intrinsic magnetoelectric coupling in the multiferroic Cc state with the easy magnetization axis controllable by the external electric field.