Regensburg 2007 – scientific programme
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MA: Fachverband Magnetismus
MA 15: Poster:ThinFilms(1-33),Transp.(34-49),ExchBias(50-56),
Spindynamics(57-70),Micro-nanostr.Mat.(71-82),
Particles/Clust.(83-88), Mag.Imag./Surface(89-96),
Spinelectronics(97-109), Theory/Micromag.(110-116),
Spinstruct/Phasetr.(117-128),Magn.Mat.(129-139),
Aniso.+Measuring(140-145), MolMag.(146-152),
MSMA(153-156)
MA 15.140: Poster
Tuesday, March 27, 2007, 15:00–19:00, Poster A
Temperature driven spin reorientation transition in thin films — •Fritz Körmann1, Stefan Schwieger2, Jochen Kienert1, and Wolfgang Nolting1 — 1Lehrstuhl Festkörpertheorie, Institut für Physik, Humboldt Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany — 2Technische Universität Ilmenau, Theoretische Physik I, Postfach 10 05 65, 98684 Ilmenau, Germany
The temperature dependent orientation of the magnetization vectors in thin ferromagnetic films is directly connected to the giant magneto resistance. Starting from an extended Heisenberg model we calculate the equilibrium angles of the magnetization and the magnetization norm of thin magnetic films quantenmechanically and self consistently. The model includes interlayer exchange (IEC) coupling, single ion anisotropies and dipolar coupling. We present a new type of temperature driven spin reorientation transition (SRT) in thin films. It can occur when the lattice and the shape anisotropy favor different easy directions of the magnetization. Due to different temperature dependencies of the two contributions the effective anisotropy may change its sign and thus the direction of the magnetization as a function of temperature may change. Contrary to the well-known reorientation transition caused by competing surface and bulk anisotropy contributions the presented SRT is also found in film systems with a uniform lattice anisotropy. We show the temperature and external field dependent reorientation of the magnetization vectors of IEC coupled films. The theory is also able to describe experimental ferromagnetic resonance results as accurately as the (classical) Landau Lifshitz equation.