Magnetic dichroism study on Mn1.8Co1.2Ga thin film using a combination of x-ray absorption and photoemission spectroscopy

Abstract

Using circularly polarised radiation and a combination of bulk-sensitive hard x-ray photoelectron spectroscopy and x-ray-absorption spectroscopy (XAS) we studied the electronic and magnetic structure of epitaxial Mn1.8Co1.2Ga thin films. Spin-resolved Bloch spectral functions, density of states as well as charge and magnetisation densities were investigated by a first-principles analysis of full potential, fully relativistic Korringa–Kohn–Rostoker calculations of the electronic structure. The valence states were experimentally investigated by using linear dichroism in the angular distribution and comparing the results to spin-resolved densities of states. The linear dichroism in the valence band enabled a symmetry analysis of the contributing states. The spectra were in good agreement with the theoretical partial density of states. The element-specific, spin-resolved, unoccupied densities of states for Co and Mn were analysed by using XAS and x-ray magnetic circular dichroism (XMCD) at the L3,2 edges. The spectra were influenced by strong correlation effects. XMCD was used to extract the site-resolved magnetic moments. The experimental values of mMn = 0.7 μB and mCo = 1.05 μB agree very well with the calculated magnetic moments. Magnetic circular dichroism in angle-resolved photoelectron spectroscopy at the Mn and Co 2p core level exhibited a pronounced magnetic dichroism and confirmed the localised character of the Mn d valence states.