Monoatomic magnetic interfaces in IrMn/Cr/Co thin films probed by grazing incidence X-ray absorption spectroscopy

TL;DR

This study uses grazing incidence X-ray absorption spectroscopy to analyze the atomic and electronic structures of IrMn/Cr/Co thin films, revealing interdiffusion, amorphous Cr behavior, and covalent bonding at the interfaces.

Contribution

It provides the first depth-resolved experimental analysis of Cr-Co interfaces in these thin films, supported by ab initio simulations, highlighting atomic interdiffusion and covalent bonding.

Findings

Interdiffusion between Cr and Co layers observed.

Cr behaves as an amorphous material in thinner layers.

Covalent bonding forms between Cr and Co, creating a CrCo alloy.

Abstract

We present depth-resolved experimental results on the atomic and electronic structures of the Co-Cr interface on four IrMn/Cr/Co thin films with variable thickness of the Cr layer. Grazing incidence X-ray absorption near edge structure near the Cr K-edge was used, and an Angstrom resolved depth-profile for this layer was obtained. An interdiffusion between chromium and cobalt layers was observed in all films, being more pronounced for samples with thinner Cr layers, where Cr behaves as an amorphous material. This causes a contraction in coordination distances in Cr near the interface with Co. In this region, a change in the electronic structure of chromium's 3d orbitals is also observed, and it appears that Cr and Co form a covalent bond resulting in a CrCo alloy. Ab initio numerical simulations support such an interpretation of the obtained experimental results.