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AM: Magnetismus
AM 11: Mikromagnetismus, Magnetisierungsprozesse und Dom
änenstrukturen I
AM 11.7: Vortrag
Mittwoch, 24. März 1999, 16:30–16:45, F5
The study of spin reorientation transition by Monte-Carlo simulations — •E. Vedmedenko1, H. P. Oepen1, A. Ghazali2, J.-C. Levy2, and J. Kirschner1 — 1Max–Planck–Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle/Saale — 2Universités Paris 7 et 6, 2 Place Jussieu, 75251 Paris Cedex 05, France
Recent investigations of ultrathin Co/Au(111) films reveal a thickness driven spin reorientation transition (SRT) from out–of–plane to in–plane state. We have studied the same kind of SRT by means of Monte–Carlo simulations of a monolayer of 3d Heisenberg spins on a triangular lattice. We obtained relaxed magnetic structures for different ratios of the perpendicular anisotropy Ea ∼ cos2 θ to the dipolar energy Ed. Our results are in good agreement with the analytical model[1] within its range of validity. We obtain, however, a more precise picture of domain size and shape dependence on the ratio Ea/Ed, because no restrictions on admissible domain patterns were made. We have performed calculations in the region where magnetostatic energy dominates and the theory of Ref.[1] cannot make any prediction. With a strong Ea, the spins form domains perpendicular to the film plane. In the transition region from out–of–plane to in–plane magnetization the magnetic structure turns into a spiral–like phase. When the dipolar energy exceeds the perpendicular anisotropy the three–dimensional spiral configuration transforms into a planar vortex structure. The evolution of the spin reorientation will be discussed. [1] Y. Yafet, E. M. Gyorgy, Phys. Rev. B 38, 9145 (1988).