Magnetism of Asymmetrically Terminated FeRh(001) Thin Films: A First-Principle Study

Rh-terminated FeRh(001) film is known to be stable in a ferromagnetic (FM) state different from a G-type antiferromagnetic (G-AFM) bulk ground state, while an Fe-terminated FeRh(001) film has the same ground state as the bulk. In this paper, we investigate the magnetic properties of asymmetrically terminated FeRh(001) films: one surface is Fe-terminated and the other is Rh-terminated. We found that the films thicker than eight monolayers (MLs) have more or less complicated magnetic configuration: the topmost three layers from the Rh-terminated surface are FM while the rest are G-AFM. In particular, the magnetic configuration of the 8-ML FeRh(001) film has lower energy than the whole-layer G-AFM and FM states by 10.2 and 0.2 meV/Fe, respectively. The magnetic configuration of the asymmetrically terminated films is explained by the magnetic energy gain due to the magnetization of the Rh atoms.