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Spin transport properties of manganese doped nanostructured magnetic semiconductors

Kervalishvili, P. J. (2010) Spin transport properties of manganese doped nanostructured magnetic semiconductors. Nano Studies, 2 . pp. 5-14. ISSN 1987-8826

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Abstract

Technology of periodic layer GaSb / Mn nanostructure getting, the structural and magneto-transport properties of thin GaMnSb films with increased content of Mn, up to 10 at. %, grown by use the laser dispersion in vacuum was studied. The structures of GaMnSb layers, regardless to the Ga replacing by the Mn acceptors, contain ferromagnetic MnSb nanoclusters and shallow acceptor defects controlled by the growth temperature were investigated. In obtained double phase ferromagnetic GaMnSb films, regardless to the case of previously studied single phase GaMnSb systems (Curie temperatures not exceeding 30 K), the anomalous Hall effect (AHE) and the AHE hysteresis at temperatures up to 300 K, as stronger as more the hole concentration, has been observed. The unusual properties of GaMnSb films have been interpreted as interaction of magnetic nanoclusters in a semiconductor matrix, where the matrix has huge concentration of free holes and magnetic ions, and which becomes stronger with increasing the holes concentration. It was investigated the magnetotransport properties of GaSb / Mn discrete alloys which should be used as ferromagnetic contacts in process of formation GaMnSb / GaSb / GaMnSb and GaMnSb / GaAs / GaMnSb three layered structures for observation of spin polarized current in perpendicular geometry. The model problem concerning the formation of a ferromagnetic cluster (magnetic polaron) consisting of the free electron bound to a non-magnetic donor impurity in an antiferromagnetic matrix was analyzed. It was shown that the magnetic polaron also produces rather long-range extended spin distortions of the antiferromagnetic background around the core. Such a magnetic polaron state can be favorable in energy in comparison to usually considered one. The studies of the structure of magnetic polarons (nanoscale ferromagnetic droplets) in magnetic semiconductors were performed with a special emphasis to frustrated lattices (square lattice with nearest-neighbor and diagonal interactions and the triangular lattice) characteristic for layered heterostructures. It was demonstrated that the magnetic polaron can produce rather extended spin distortions of the antiferromagnetic background around its ferromagnetic core. The characteristic size of this ‘coat’ decreases for stronger next-nearest neighbor interaction or with increase of magnetic anisotropy.

Item Type:Article
Subjects:Physical Science > Nanomagnetics
Divisions:Faculty of Engineering, Science and Mathematics > School of Physics
ID Code:11749
Deposited By:Professor Levan Chkhartishvili
Deposited On:20 Jan 2012 17:13
Last Modified:20 Jan 2012 17:13

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