Epitaxial strain effects in the spinel ferrites CoFe2O4 and NiFe2O4 from first principles

TL;DR

This study uses first-principles calculations to explore how epitaxial strain influences magnetic anisotropy and magnetostriction in CoFe2O4 and NiFe2O4 spinel ferrites, aligning well with experimental data.

Contribution

It provides a detailed computational analysis of strain effects on magnetic properties in inverse spinel ferrites, confirming experimental trends and demonstrating the effectiveness of LSDA+U and GGA+U methods.

Findings

Tensile strain favors perpendicular magnetic anisotropy.

Compressive strain favors in-plane magnetic orientation.

Calculated magnetostriction constants agree with experimental data.

Abstract

The inverse spinels CoFe2O4 and NiFe2O4, which have been of particular interest over the past few years as building blocks of artificial multiferroic heterostructures and as possible spin-filter materials, are investigated by means of density functional theory calculations. We address the effect of epitaxial strain on the magneto-crystalline anisotropy and show that, in agreement with experimental observations, tensile strain favors perpendicular anisotropy, whereas compressive strain favors in-plane orientation of the magnetization. Our calculated magnetostriction constants $\lambda_{100}$ of about -220 ppm for CoFe2O4 and -45 ppm for NiFe2O4 agree well with available experimental data. We analyze the effect of different cation arrangements used to represent the inverse spinel structure and show that both LSDA+U and GGA+U allow for a good quantitative description of these materials. Our results open the way for further computational investigations of spinel ferrites.