Regensburg 2007 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 10: Spinelectronics/Spininjection in Heterostructures
MA 10.13: Vortrag
Montag, 26. März 2007, 18:15–18:30, H23
Curie temperature vs conductivity relation: (Ga,Mn)As alloy — •Josef Kudrnovsky1, Georges Bouzerar2, and Ilja Turek3 — 1Institute of Physics AS CR, Prague, Czech Republic — 2Institut Laue Langevin and Laboratoire Luis Neel, Grenoble, France — 3Institute of Physics of Materials AS CR, Brno, Czech Republic
We evaluate from first principles the Curie temperature and conductivity of (Ga,Mn)As alloys at various levels of annealing, from as-grown samples to samples with very low compensation.
The Curie temperature was estimated in the framework of the local RPA approach [1] starting from the classical random Heisenberg model constructed from first-principles [2] and assuming that compensating defects are Mn-interstitials [3].
Conductivity is estimated using Kubo-Greenwood formula with the impurity-induced vertex-part [4] and assuming the antiparallel orientation of Mn(Ga) and Mn-interstitial moments. Various stages of annealing are simulated by the effective Mn-concentration and compensation ratio obtained from the experiment [5].
Assuming also a small amount of As-antisites, a good quantitative agreement between theory and experiment [5] was obtained thus giving a strong theoretical support to the carrier-induced model of ferromagnetism in (Ga,Mn)As diluted magnetic semiconductors.
References
[1] Europhysics Letters 69 (2005) 812 [2] Phys. Rev. B69 (2004) 115208 [3] Phys. Rev. B72 (2005) 125207 [4] J.Phys.: Condens. Matter 16 (2004) S5607 [5] Appl. Phys. Letters 81 (2002) 4991