Title :
Atomic Spin Scattering and Giant Magnetoresistance in Magnetic Semiconductors
Author :
Foygel, M. ; Niggemann, J. ; Petukhov, A.G.
Author_Institution :
Phys. Dept., South Dakota Sch. of Mines & Technol., Rapid City, SD
fDate :
6/1/2007 12:00:00 AM
Abstract :
We studied electrical transport in dilute magnetic semiconductors, which is determined by scattering free carriers by localized magnetic moments. While calculating the scattering time and the mobility of the majority and minority-spin carriers, we took into account both the effects of thermal spin fluctuations and of the spatial disorder of magnetic atoms. These effects are responsible for the magnetic-field dependence of electrical resistivity. Namely, the application of the external magnetic field suppresses the thermodynamic spin fluctuations, thus promoting negative magnetoresistance (MR). Simultaneously, scattering by built-in spatial fluctuations of the atomic spins increases with the magnetic field. The latter effect is due to the growth of the magnitude of random local Zeeman splittings with the magnetic field. It promotes positive MR. We discuss the role of the above effects on MR of semiconductors where magnetic impurities are isoelectronic
Keywords :
Zeeman effect; carrier mobility; giant magnetoresistance; magnetic impurities; magnetic moments; minority carriers; semimagnetic semiconductors; spin fluctuations; thermodynamic properties; atomic spin scattering; built-in spatial fluctuations; carrier mobility; dilute magnetic semiconductors; electrical resistivity; electrical transport; giant magnetoresistance; isoelectronic magnetic impurities; localized free carrier scattering; magnetic atom spatial disorder; magnetic moments; majority-spin carriers; minority-spin carriers; negative magnetoresistance; positive magnetoresistance; random local Zeeman splittings; thermal spin fluctuations; Couplings; Fluctuations; Giant magnetoresistance; Magnetic fields; Magnetic materials; Magnetic semiconductors; Saturation magnetization; Scattering; Semiconductor impurities; Thermodynamics; Magnetoresistance; semiconductor; spin scattering;
Journal_Title :
Magnetics, IEEE Transactions on
DOI :
10.1109/TMAG.2007.892941