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Title: Point defects as a test ground for the local density approximation +U theory: Mn, Fe, and V{sub Ga} in GaN

Abstract

Electronic structure of the Mn and Fe ions and of the gallium vacancy V{sub Ga} in GaN was analysed within the GGA + U approach. First, the +U term was treated as a free parameter, and applied to p(N), d(Mn), and d(Fe). The band gap of GaN is reproduced for U(N) ≈ 4 eV. The electronic structure of defect states was found to be more sensitive to the value of U than that of the bulk states. Both the magnitude and the sign of the U-induced energy shifts of levels depend on occupancies, and thus on the defect charge state. The energy shifts also depend on the hybridization between defect and host states, and thus are different for different level symmetries. In the case of V{sub Ga}, these effects lead to stabilization of spin polarization and the “negative-U{sub eff}” behavior. The values of Us were also calculated using the linear response approach, which gives U(Fe) ≈ U(Mn) ≈ 4 eV. This reproduces well the results of previous hybrid functionals calculations. However, the best agreement with the experimental data is obtained for vanishing or even negative U(Fe) and U(Mn)

Authors:
;  [1];  [1];  [2]
  1. Institute of Physics PAS, 02-668 Warsaw (Poland)
  2. (Poland)
Publication Date:
OSTI Identifier:
22308906
Resource Type:
Journal Article
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 141; Journal Issue: 11; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-9606
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; APPROXIMATIONS; CHARGE STATES; DEFECTS; ELECTRONIC STRUCTURE; GALLIUM; GALLIUM NITRIDES; HYBRIDIZATION; IRON IONS; SPIN ORIENTATION; STABILIZATION

Citation Formats

Volnianska, O., Zakrzewski, T., Boguslawski, P., and Institute of Physics, Kazimierz Wielki University, 85-072 Bydgoszcz. Point defects as a test ground for the local density approximation +U theory: Mn, Fe, and V{sub Ga} in GaN. United States: N. p., 2014. Web. doi:10.1063/1.4895790.
Volnianska, O., Zakrzewski, T., Boguslawski, P., & Institute of Physics, Kazimierz Wielki University, 85-072 Bydgoszcz. Point defects as a test ground for the local density approximation +U theory: Mn, Fe, and V{sub Ga} in GaN. United States. doi:10.1063/1.4895790.
Volnianska, O., Zakrzewski, T., Boguslawski, P., and Institute of Physics, Kazimierz Wielki University, 85-072 Bydgoszcz. Sun . "Point defects as a test ground for the local density approximation +U theory: Mn, Fe, and V{sub Ga} in GaN". United States. doi:10.1063/1.4895790.
@article{osti_22308906,
title = {Point defects as a test ground for the local density approximation +U theory: Mn, Fe, and V{sub Ga} in GaN},
author = {Volnianska, O. and Zakrzewski, T. and Boguslawski, P. and Institute of Physics, Kazimierz Wielki University, 85-072 Bydgoszcz},
abstractNote = {Electronic structure of the Mn and Fe ions and of the gallium vacancy V{sub Ga} in GaN was analysed within the GGA + U approach. First, the +U term was treated as a free parameter, and applied to p(N), d(Mn), and d(Fe). The band gap of GaN is reproduced for U(N) ≈ 4 eV. The electronic structure of defect states was found to be more sensitive to the value of U than that of the bulk states. Both the magnitude and the sign of the U-induced energy shifts of levels depend on occupancies, and thus on the defect charge state. The energy shifts also depend on the hybridization between defect and host states, and thus are different for different level symmetries. In the case of V{sub Ga}, these effects lead to stabilization of spin polarization and the “negative-U{sub eff}” behavior. The values of Us were also calculated using the linear response approach, which gives U(Fe) ≈ U(Mn) ≈ 4 eV. This reproduces well the results of previous hybrid functionals calculations. However, the best agreement with the experimental data is obtained for vanishing or even negative U(Fe) and U(Mn)},
doi = {10.1063/1.4895790},
journal = {Journal of Chemical Physics},
issn = {0021-9606},
number = 11,
volume = 141,
place = {United States},
year = {2014},
month = {9}
}