Magnetic dichroism study on Mn$_{1.8}$Co$_{1.2}$Ga thin film using a combination of X-ray absorption and photoemission spectroscopy

TL;DR

This study combines advanced spectroscopic techniques and first-principles calculations to analyze the electronic and magnetic structures of Mn$_{1.8}$Co$_{1.2}$Ga thin films, revealing element-specific magnetic moments and the localized nature of Mn $d$ states.

Contribution

It provides a comprehensive analysis of the electronic and magnetic structure of Mn-Co-Ga thin films using combined experimental and theoretical methods, highlighting the element-specific magnetic moments and the role of correlation effects.

Findings

Good agreement between experimental and theoretical density of states.

Element-specific magnetic moments for Mn and Co were determined.

Localized character of Mn $d$ states confirmed by magnetic dichroism.

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 Mn$_{1.8}$Co$_{1.2}$Ga 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 $L_{3,2}$ edges. The spectra were influenced by strong correlation effects. XMCD was used to extract the site resolved magnetic moments. The experimental values of $m_{\rm Mn}=0.7\:\mu_B$ and $m_{\rm Co}=1.05\:\mu_B$ 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.