Surface-termination dependent magnetism and strong perpendicular magnetocrystalline anisotropy of a FeRh (001) thin film: A density-functional study

TL;DR

This study uses density-functional theory to explore how surface termination affects the magnetism and magnetocrystalline anisotropy of FeRh (001) thin films, revealing strong perpendicular anisotropy in Rh-terminated films.

Contribution

It demonstrates the dependence of magnetic properties on surface termination and film thickness, highlighting the dominant role of superexchange, Zener interaction, and magnetic energy in determining magnetic phases.

Findings

Rh-terminated films exhibit ferromagnetism with strong perpendicular MCA.

Magnetic anisotropy energy is significantly larger than in typical 3d metals.

Magnetic phases result from interplay of superexchange, Zener interaction, and magnetic energy.

Abstract

Magnetism of FeRh (001) films strongly depends on film thickness and surface terminations. While magnetic ground state of bulk FeRh is G-type antiferromagnetism, the Rh-terminated films exhibit ferromagnetism with strong perpendicular MCA whose energy +2.1 meV/$\Box$ is two orders of magnitude greater than 3$d$ magnetic metals, where $\Box$ is area of two-dimensional unit cell. While Goodenough-Kanamori-Anderson rule on the superexchange interaction is crucial in determining the magnetic ground phases of FeRh bulk and thin films, the magnetic phases are results of interplay and competition between three mechanisms - the superexchange interaction, the Zener direct-interaction, and magnetic energy gain.