Fermi Surface-Brillouin Zone Interactions in 2/1-2/1-2/1 Bergman-Type Approximant Na27Au27Ga31

U. Mizutania, H. Satob, M. Inukaic, E.S. Zijlstrad, Q. Line, J.D. Corbette and G.J. Millere aNagoya Industrial Science Research Institute, 1-13 Yotsuya-dori, Chikusa-ku, Nagoya, 464-0819, Japan bAichi University of Education, Kariya-shi, Aichi, 448-8542, Japan cNagoya Institute of Technology, Department of Frontier Materials, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan dTheoretical Physics, University of Kassel, 34132 Kassel, Germany eAmes Laboratory, US-DOE & Department of Chemistry, Iowa State University, U.S.A.

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The X-ray diffraction studies on a newly synthesized Na26Au25Ga29 single crystal revealed the formation of a single phase 2/1-2/1-2/1 Bergman-type approximant and the presence of Au/Ga mixed occupancies in its unit cell containing 680 atoms. The structure model of the 2/1-2/1-2/1 approximant with composition Na27Au27Ga31 was constructed by eliminating the chemical disorder with a minimum sacrifice of composition displacement. The full potential linearized augmented plane wave electronic structure calculations with subsequent full potential linearized augmented plane wave-Fourier analysis were performed for the 2/1-2/1-2/1 approximant Na27Au27Ga31 with space group Pa3̅. The square of the Fermi diameter (2kF)2, electrons per atom ratio e/a and the critical reciprocal lattice vector |G|2 are determined. A shallow pseudogap at the Fermi level was interpreted as originating from interference of electrons having (2kF)2=109.2±1.0 with sets of lattice planes with |G|2's centered at 108. The effective e/a value for the compound is found to be 1.76 in good agreement with 1.73 derived from a composition average of (e/a)Na=1.0, (e/a)Au=1.0 and (e/a)Ga=3.0.

DOI: 10.12693/APhysPolA.126.535 PACS numbers: 71.23.Ft, 71.20.Dg, 71.15.Mb