The non-metal-to-metal and Vice-Versa transitions in a GaMnAs layer

• Published in: Journal of superconductivity and novel magnetism Vol. 20; no. 6; pp. 421 - 427
• Main Authors: DIAS CABRAL, E, DA CUNHA LIMA, I. C, BOSELLI, M. A, DA CUNHA LIMA, A. T, GHAZALI, A
• Format: Conference Proceeding Journal Article
• Language: English
• Published: New York, NY Springer 01-08-2007; Springer Verlag
• Subjects: Condensed Matter; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electron states; Exact sciences and technology; Metal-insulator transitions and other electronic transitions; Physics; Gallium arsenides; Magnetization; Hole density; Metal non metal transition; Self consistency; Spectral functions; Electronic density of states; Multiple scattering; Thin films; Free carrier; 72.15.Rn; Polarized spin; Manganese arsenides; 73.61.Ey; Chemical composition; Carrier density; Spin state; 75.75.+a; GaMnAs, Metal-non-metal transitions, Multiple-scattering, 75.50.Pp; multiple-scattering; metal-non-metal transitions; GaMnAs
• ISSN: 1557-1939; 1557-1947
• DOI: 10.1007/s10948-007-0241-8

A self-consistent calculation of the density of states and the spectral density function is performed in a two-dimensional spin-polarized hole system based on a multiple-scattering approximation. Using parameters corresponding to GaMnAs thin layers, a wide range of Mn concentrations and hole densities have been explored to understand the nature, localized or extended, of the spin-polarized holes at the Fermi level for several values of the average magnetization of the Mn system. If the impurity concentration is below a certain threshold, the increase of the magnetization does not lead to a significant change in the localized character of the spin-polarized states. Above this threshold, we reach conditions allowing the occurrence of spin-polarized extended states at the Fermi level-more properly extended states in a very dirty metal-which are very sensitive to the average magnetization. The occurrence of a metal-to-non-metal transition has been surveyed around an optimum combination of the Mn concentration and the free carriers density.