Compensation, interstitial defects, and ferromagnetism in diluted ferromagnetic semiconductors

Georges Bouzerar, Timothy Ziman, and Josef Kudrnovský
Phys. Rev. B 72, 125207 – Published 23 September 2005

Abstract

We present a quantitative theory for ferromagnetism in diluted III-V ferromagnetic semiconductors in the presence of the two types of defects commonly supposed to be responsible for compensation: As antisites and Mn interstitials. In each case we reduce the description to that of an effective random Heisenberg model with exchange integrals between active magnetic impurities provided by ab initio calculation. The effective magnetic Hamiltonian is then solved by a semianalytical method (locally self-consistent random-phase approximation), where disorder is treated exactly. Measured Curie temperatures are shown to be inconsistent with the hypothesis that As antisites provide the dominant mechanism for compensation. In contrast, if we assume that Mn interstitials are the main source for compensation, we obtain a very good agreement between the calculated Curie temperature and the measured values, in both as-grown and annealed samples.

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  • Received 31 May 2005

DOI:https://doi.org/10.1103/PhysRevB.72.125207

©2005 American Physical Society

Authors & Affiliations

Georges Bouzerar1,2,*, Timothy Ziman2,†, and Josef Kudrnovský2,3,‡

  • 1Laboratoire Louis Néel, 25 Avenue des Martyrs, Boîte Postale 166, 38042 Grenoble Cedex 09, France
  • 2Institut Laue Langevin, Boîte Postale 156, 38042 Grenoble, France
  • 3Institute of Physics, Academy of Sciences of the Czech Republic, Na Solvance 2, CZ-182 21 Prague 8, Czech Republic

  • *Email address: georges.bouzerar@grenoble.cnrs.fr orbouzerar@ill.fr
  • Email address: ziman@ill.fr
  • Email address: kudrnov@fzu.cz

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Issue

Vol. 72, Iss. 12 — 15 September 2005

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