Electron momentum-space densities and Fermi surface of Li100xMgx (0<~x<~40) alloys: Compton scattering experiment versus theory

G. Stutz, F. Wohlert, A. Kaprolat, W. Schülke, Y. Sakurai, Y. Tanaka, M. Ito, H. Kawata, N. Shiotani, S. Kaprzyk, and A. Bansil
Phys. Rev. B 60, 7099 – Published 1 September 1999
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Abstract

Directional Compton profiles (CP’s) of Li100xMgx(0<~x<~40) were measured for (11)12 directions of the momentum transfer q with (0.14) 0.16 a.u. (a.u.=atomic units: ħ=e=m=1) momentum space resolution using synchrotron x rays, monochromatized to (31) 59 keV (values in brackets refer to x=0). The total experimental valence electron CP’s, their second derivatives, and the associated directional differences were compared with the corresponding Korringa-Kohn-Rostoker–coherent-potential-approximation–local-density-approximation (KKR–CPA–LDA) computations. Discrepancies between measurements and calculations are partly traced back to an inadequate treatment of electron correlation effects within the LDA framework. The three-dimensional (3D) valence-electron momentum density, ρ(p), as well as the 3D occupation number density N(k), were reconstructed from experimental data using the Fourier-Bessel method. The reconstructed ρ(p)’s exhibit evidence of higher momentum components due to 110 umklapp processes, whose variations with x are in reasonable agreement with the KKR-CPA calculations. The experimental N(k)’s provide a direct measure of the Fermi-surface anisotropy and show the presence of necks on the 110 Brillouin-zone boundaries for x>~13 in good accord with 2D positron annihilation experiments.

  • Received 4 January 1999

DOI:https://doi.org/10.1103/PhysRevB.60.7099

©1999 American Physical Society

Authors & Affiliations

G. Stutz*, F. Wohlert, A. Kaprolat, and W. Schülke

  • Institute of Physics, University of Dortmund, D-44221 Dortmund, Germany

Y. Sakurai and Y. Tanaka

  • The Institute of Physical and Chemical Research, Wako, Saitama 351-01, Japan

M. Ito

  • Faculty of Science, Himeji Institute of Technology, Kamigohri, Hyogo 678-12, Japan

H. Kawata

  • Photon Factory, National Laboratory for High Energy Physics, Tsukuba, Ibaraki 305, Japan

N. Shiotani

  • Tokyo University of Fisheries, Kounan, Minato, Tokyo 108, Japan

S. Kaprzyk and A. Bansil

  • Department of Physics, Northeastern University, Boston, Massachusetts 02115

  • *Present address: Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, 5000 Cordoba, Argentina.
  • Present address: Academy of Mining and Metallurgy, Institute of Physics and Nuclear Techniques, Krakow, Poland.

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Vol. 60, Iss. 10 — 1 September 1999

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