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Onset of Ferromagnetism in Low-Doped Ga1-xMnxAs
B L Sheu1, R C Myers, J-M Tang
1Physics Department and Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Abstract:
We develop a quantitatively predictive theory for impurity-band ferromagnetism in the low-doping regime of Ga1-xMnxAs. We compare it with measurements of a series of samples whose compositions span the transition from paramagnetic insulating to ferromagnetic conducting behavior. The theoretical Curie temperatures depend sensitively on the local fluctuations in the Mn-hole binding energy, which originate from Mn disorder and As antisite defects. The experimentally determined hopping energy is an excellent predictor of the Curie temperature, in agreement with the theory.
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