Dresden 2009 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 17: Magnetic Thin Films I

MA 17.2: Vortrag

Mittwoch, 25. März 2009, 10:30–10:45, HSZ 04

On origin of perpendicular anisotropy in Fe_1−xCo_x alloy films grown on Pd(001), Ir(001) and Rh(001) substrates — •Fikret Yildiz, Marek Przybylski, and Jürgen Kirschner — Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle, Germany

We have shown that the Fe_1−xCo_x alloy films of the composition around x = 0.5 show a maximum perpendicular anisotropy when their cubic lattice is tetragonally distorted by growing the films on mismatching substrates like Pd(001), Ir(001) and Rh(001) [1,2]. The easy magnetization axis reorients at different temperatures showing that the perpendicular anisotropy depends on distortion of cubic symmetry, i.e. on the c/a ratio. For the same composition the uniaxial anisotropy reaches maximum for the Fe_0.5Co_0.5 films grown on Rh(001) (c/a = 1.24). To verify this hypothesis we have grown a buffer layer of Pd a few ML thick on Rh(001). Low energy electron diffraction (LEED) pattern shows that the spots are exactly at the same positions as for the clean Rh(001) substrate which proves that the lattice constant of the Pd-buffer is the same as the one of the Rh(001) substrate. The hysteresis loops of the Fe_0.5Co_0.5 films grown on top of it are just the same as the loops measured for the films grown directly on the Rh(001) substrate. This confirms that the strong perpendicular anisotropy originates from an appropriate tetragonal distortion.

[1] A. Winkelmann, M. Przybylski, F. Luo, Y. Shi, J. Kirschner, Phys. Rev. Lett. 96, 257205 (2006) [2] F. Yildiz, F. Luo, C. Tieg, R. Abrudan, X. L. Fu, A. Winkelmann, M. Przybylski, J. Kirschner, Phys. Rev. Lett. 100, 037205 (2008)