Comparative electronic structure investigation of intermetallic CrGa₄ and Cr metal

Yu-Xun Chen^1*, Abhijeet Shelke¹, Truc Ly Nguyen¹, Fan-Hsiu Chang¹, Yi-Ting Cheng², Tun-Wen Pi¹, Masato Yoshimura¹, Nozomu Hiraoka¹, Hong-Ji Lin¹, Chien-Te Chen¹, Chia-Nung Kuo³, Chin-Shan Lue³, Ashish Chainani¹

¹National Synchrotron Radiation Research Center (NSRRC), Hsinchu, Taiwan
²Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei, Taiwan
³Department of Physics, National Cheng Kung University, Tainan, Taiwan

* Presenter:Yu-Xun Chen, email:chen.yx@nsrrc.org.tw

We investigate the electronic structure of a Hume-Rothery type gallium-rich intermetallic CrGa₄ and compare it with elemental Cr metal, using hard X-ray photoelectron spectroscopy (HAXPES) and X-ray absorption spectroscopy (XAS). The HAXPES Cr 2p core-levels of CrGa₄ exhibit a lower binding energy than Cr metal, and indicate Ga to Cr charge transfer in CrGa₄. Both materials show asymmetric Doniach–Sunjic line-shapes, with a larger asymmetry for Cr metal. The results indicate a lower density of states at the Fermi-level in CrGa₄, confirmed by measured valence band spectra. The Cr 3s spectra show an exchange-split local magnetic moment in both materials, and a Van Vleck analysis gives Cr spin moment of 1.136 μB in CrGa₄ and 0.758 μB in elemental Cr. The Cr L-edge XAS of CrGa₄ shows evidence for crystal-field splitting, unlike elemental Cr metal. The valence band of CrGa₄ shows the Cr 3d band at 1.4 eV binding energy with a pseudogap at Fermi-level, and it could be simulated using reported partial density of states thus identifying the Cr 3d, Ga 4s, and Ga 4p contributions.

Keywords: Hard X-ray Photoemission Spectroscopy, X-ray Absorption Spectroscopy, intermetallic