Publications in Scientific Journals:

L. Bergqvist, P.A. Korzhavyi, B. Sanyal, S. Mirbt, I.A. Abrikosov, L. Nordström, E.A. Smirnova, P. Mohn, P. Svedlindh, O. Eriksson:
"Magnetic and electronic structure of (Ga1-xMnx)As";
Physical Review B, 67 (2003), 205201-1 - 205201-9.

English abstract:
We present theoretical calculations of the magnetic and electronic structure of Mn-doped GaAs ~in the
zinc-blende structure!. The magnetic properties are shown to be very sensitive to structural defects, in particular,
As antisite defects and Mn at interstitial positions. Only when considering such defects can the experimental
magnetic moments be reproduced by first-principles theory. We present a simple model for understanding
the connection between the magnetic ordering and the As antisites, and the way in which the defects help to
stabilize a partial disordered local-moment state. The connection between the energetics of the Mn substitution
and the As antisite concentration is also analyzed. In addition, we compare the calculated magnetic properties
and electronic structures of Mn situated on substitutional sites ~Mn replacing a Ga atom! and on interstitial
sites, where in agreement with observations the interstitial site is found to be less favorable. Finally, combining
our first-principles calculations of the spin-wave excitation energies with a classical Heisenberg Hamiltonian
we have calculated interatomic exchange interactions, and using Monte Carlo simulations we present theoretical
values of the critical temperature as a function of Mn concentration.
DOI: 10.1103/PhysRevB.67.205201 PACS number~s!: 75.25.1z, 75.70.2i, 85.75.2d

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