Magnetic dichroism study on Mn_1.8Co_1.2Ga thin film using a combination of x-ray absorption and photoemission spectroscopy

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.