Hamburg 2001 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 5: III-V Halbleiter I
HL 5.2: Vortrag
Montag, 26. März 2001, 10:45–11:00, S6
Theory of (III,Mn)V Semiconductor Ferromagnetism — •Jürgen König1, Hsiu-Hau Lin2, John Schliemann1, and Allan MacDonald1 — 1Department of Physics, University of Texas, Austin, USA — 2Department of Physics, National Tsing-Hua University, Taiwan
Carrier-induced ferromagnetism has been observed in several (III,Mn)V semiconductors. We review the theoretical picture that emerges from a model with kinetic-exchange coupling between localized Mn spins and valence-band carriers. We discuss the validity of a mean-field approximation widely used in the literature, and validity limits for the simpler RKKY model in which only Mn spins appear explicitly. Our conclusions are based in part on our analysis [1,2] of the system’s elementary spin excitations.
Predictions of mean-field theory suggest a route toward room-temperature ferromagnetism. We use theoretical estimates of spin-wave energies and Monte-Carlo simulations [3] to demonstrate that collective fluctuations, neglected by mean-field theory, place important limits on the critical temperature.
[1] J. König, H.H. Lin, and A.H. MacDonald, Phys. Rev. Lett. 84, 5628 (2000). [2] J. König, H.H. Lin, and A.H. MacDonald, cond-mat/0010471. [3] J. Schliemann, J. König, H.H. Lin, and A.H. MacDonald, cond-mat/0010036.