Effects of biaxial strain on the improper multiferroicity in h-LuFeO3 films

TL;DR

This study investigates how biaxial strain influences the multiferroic properties of h-LuFeO3 films, revealing that compressive strain enhances ferrodistortion, electric polarization, and affects magnetic moments, advancing understanding of strain-multiferroicity coupling.

Contribution

It introduces restrained thermal expansion as a method to study strain effects in multiferroic thin films, providing new insights into strain-induced property modifications in h-LuFeO3.

Findings

Compressive biaxial strain enhances ferrodistortion.

Strain increases electric polarization.

Strain reduces canting of ferromagnetic moments.

Abstract

Elastic strain is potentially an important approach in tuning the properties of the improperly multiferroic hexagonal ferrites, the details of which have however been elusive due to the experimental difficulties. Employing the method of restrained thermal expansion, we have studied the effect of isothermal biaxial strain in the basal plane of h-LuFeO3 (001) films. The results indicate that a compressive biaxial strain significantly enhances the ferrodistortion, and the effect is larger at higher temperatures. The compressive biaxial strain and the enhanced ferrodistortion together, cause an increase in the electric polarization and a reduction in the canting of the weak ferromagnetic moments in h-LuFeO3, according to our first principle calculations. These findings are important for understanding the strain effect as well as the coupling between the lattice and the improper multiferroicity in h-LuFeO3. The experimental elucidation of the strain effect in h-LuFeO3 films also suggests that the restrained thermal expansion can be a viable method to unravel the strain effect in many other epitaxial thin film materials.