Photoemission spectroscopy and {\it ab-initio} simulation of CrFeVGa and CoFeVSb : A Comparative Study

We present a comprehensive photoemission study of two Vanadium-based quaternary Heusler alloys, CrFeVGa and CoFeVSb, which are highly promising candidates for spintronics and topological quantum applications. CrFeVGa exhibits large anomalous Hall conductivity due to the large Berry curvature originating from its non-trivial topological bands. In contrast, CoFeVSb displays a spin-valve-like behavior alongside excellent thermoelectric properties, such as ultra-low thermal conductivity and high power factor at room temperature. By utilizing synchrotron x-ray photoemission spectroscopy and resonant photoemission spectroscopy, we have investigated the core levels and valence band of both the alloys. Our analysis shows that the V 3<i>d</i>states are primarily responsible for the electronic states at the Fermi level which result in the high spin polarization, consistent with our theoretical predictions. The presence of the Fermi edge in the valence band spectra in both the systems confirms the predicted metallic or half/semi-metallic features. The observed spectra match qualitatively with our simulated partial density of states. A close inspection of the temperature dependent valence band spectra indicates that some of the intriguing bulk properties reported earlier on these two systems are intimately connected with their unique band structure topology. This in turn facilitate a deeper insight into the origin of such interesting properties of these alloys. Such direct measurements of electronic structure provide a guiding platform towards a better understanding of the anomalous properties of any material in general.