Electronic structure and spectroscopy of the quaternary Heusler alloy Co₂Cr_1−<i>x</i>Fe_<i>x</i>Al

Abstract

Quaternary Heusler alloys Co$_2$Cr$_{1-x}$Fe$_{x}$Al with varying Cr to Fe\nratio $x$ were investigated experimentally and theoretically. The electronic\nstructure and spectroscopic properties were calculated using the full\nrelativistic Korringa-Kohn-Rostocker method with coherent potential\napproximation to account for the random distribution of Cr and Fe atoms as well\nas random disorder. Magnetic effects are included by the use of spin dependent\npotentials in the local spin density approximation.\n Magnetic circular dichroism in X-ray absorption was measured at the $L_{2,3}$\nedges of Co, Fe, and Cr of the pure compounds and the $x=0.4$ alloy in order to\ndetermine element specific magnetic moments. Calculations and measurements show\nan increase of the magnetic moments with increasing iron content. Resonant\n(560eV - 800eV) soft X-ray as well as high resolution - high energy ($\\geq\n3.5$keV) hard X-ray photo emission was used to probe the density of the\noccupied states in Co$_2$Cr$_{0.6}$Fe$_{0.4}$Al.\n