Dresden 2006 – wissenschaftliches Programm

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MA: Magnetismus

MA 20: Poster: Films(1-36) Transp(37-56) Ex.Bias(57-67) Spindyn(68-80) Micromag(81-95) Particle(96-109) Imag.+Surface(110-113) Spinelectr(114-122) Theory+Micromag(123-131) Spinstr+Aniso(132-142) MagMat(143-156) Meas(157,158) MolMag+Kondo(159-162) Postdead(163-)

MA 20.120: Poster

Dienstag, 28. März 2006, 15:15–19:15, P1

Phenomenological analysis of reorientation transitions, multidomain states and switching processes in diluted magnetic semiconductor films — •I.E. Dragunov¹, U.K. Rößler², and A.N. Bogdanov^2,1 — ¹Donetsk Institute for Physics and Technology, R. Luxemburg 72, 83114 Donetsk, Ukraine — ²IFW Dresden, P.O. Box 270116, D-01171 Dresden, Germany

Magnetization switching processes in diluted magnetic semiconductors materials like (Ga,Mn)As films and devices are strongly influenced by specific reorientation effects due to a competition between uniaxial and cubic anisotropies. The magnetic phase diagrams of such systems, calculated within a phenomenological theory, include a region of four-phase domain structure with four adjoining areas of two-phase domains as well as several regions with coexisting metastable states. Equilibrium parameters of the domain structures as functions of applied field and ratios between the different types of magnetic anisotropies have been used to analyze the magnetization processes observed in diluted magnetic semiconductors. We propose that a remarkable transformation of the internal domain wall structure within the metastable regions of the magnetic phase diagram could be used in (Ga,Mn)As microdevices based on domain walls pinned in constrictions. For (Ga,Mn)As epilayers with perpendicular anisotropy the parameters of the stripe domain structures have been derived as functions of a bias field.