Berlin 2005 – wissenschaftliches Programm
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MA: Magnetismus
MA 20: Poster:Schichten(1-29),Spintrsp(30-45),Ex-Bias(46-63),Spindyn(64-75),Mikromat.(76-80),Cluster(81-94),Abbv.(95-99),Obflm(100-02),SpElek.(103-09),E-Theo(110-14),Mikromag.(115-16),Spin+PÜ(117-26),Mag.Mat.(127-51),Meth.(152-55),Mol.Mag(156-59),Kondo(160-65
MA 20.31: Poster
Montag, 7. März 2005, 14:00–18:00, Poster TU C
Aspects of spin-dependent scattering in magnetic nano-constrictions — •Jamal Berakdar1, V.K. Dugaev1, J. Barnas2, M. Vieira3, W. Dobrowolski4, and V.F. Mitin5 — 1MPI für Mikrostrukturphysik, Halle, Germany — 2A. Mickiewicz University, Poznan, Poland — 3ISEL, Lisbon, Portugal — 4Institute of Physics, PAN, Warsaw, Poland — 5Institute of Semiconductor Physics, Kiev, Ukraine
Magnetoresistance of nanowires and nanoconstrictions based on GaMnAs magnetic semiconductors can be as large as 2000% [1]. We analyze theoretically this effect in terms of a thin domain wall model [2] and under the depletion conditions. The model is valid for long wavelengths of charge carriers as compared to the domain wall width (realizable for magnetic semiconductors). Largest magnetoresistance occurs when the splitting of electron bands is large enough to ensure full spin polarization of holes in p-type materials. Such a situation is realizable in heavily Mn-doped and strongly compensated GaMnAs semiconductors. We calculated the resistance of the domain wall as a function of the polarization and the hole density. Spin-orbit interaction is shown to play an important role in the magnetoresistance. We also discuss the role of localization corrections related to disorder. At low temperatures the magnetoresistance is strongly influenced by localization effects. Magnetoresistance can be electrically controlled by a gate in the nanoconstriction region.
[1] C. Ruester, T. Borzenko, et al. Phys. Rev. Lett. 91, 216602 (2003).
[2] V.K. Dugaev, J. Berakdar, J. Barnas, Phys. Rev. B 68, 104434 (2003).