Giant interfacial perpendicular magnetic anisotropy in Fe/CuIn$_{1-x}$Ga$_x$Se$_2$ beyond Fe/MgO

TL;DR

This study uses first-principles calculations to identify Fe/CuInSe2 as a heterostructure with giant perpendicular magnetic anisotropy, surpassing traditional Fe/MgO, driven by specific orbital configurations and interfacial Se atom positions.

Contribution

The paper reveals that Fe/CuInSe2 exhibits a significantly larger interfacial perpendicular magnetic anisotropy than Fe/MgO, with detailed analysis linking this to orbital configurations and Se atom positioning.

Findings

Fe/CuInSe2 has a $K_i$ of ~2.3 mJ/m^2, larger than Fe/MgO.

Most studied systems follow Bruno's relation, highlighting minority-spin contributions.

Large $K_i$ in Fe/CuInSe2 is due to specific $3d$-orbital configurations.

Abstract

We study interfacial magnetocrystalline anisotropies in various Fe/semiconductor heterostructures by means of first-principles calculations. We find that many of those systems show perpendicular magnetic anisotropy (PMA) with a positive value of the interfacial anisotropy constant $K_{\rm i}$. In particular, the Fe/CuInSe$_2$ interface has a large $K_{\rm i}$ of $\sim 2.3\,{\rm mJ/m^2}$, which is about 1.6 times larger than that of Fe/MgO known as a typical system with relatively large PMA. We also find that the values of $K_{\rm i}$ in almost all the systems studied in this work follow the well-known Bruno's relation, which indicates that minority-spin states around the Fermi level provide dominant contributions to the interfacial magnetocrystalline anisotropies. Detailed analyses of the local density of states and wave-vector-resolved anisotropy energy clarify that the large $K_{\rm i}$ in Fe/CuInSe$_2$ is attributed to the preferable $3d$-orbital configurations around the Fermi level in the minority-spin states of the interfacial Fe atoms. Moreover, we have shown that the locations of interfacial Se atoms are the key for such orbital configurations of the interfacial Fe atoms.