Regensburg 2010 – scientific programme

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MA: Fachverband Magnetismus

MA 18: Magnetic Thin Films II

MA 18.9: Talk

Wednesday, March 24, 2010, 17:15–17:30, H3

Induced Magnetic Anisotropy in Amorphous Fe₂₄Co₆₈Zr₈ Thin Films — •Yu Fu¹, Igor Barsukov¹, Marina Spasova¹, Hossein Raanaei², Björgvin Hjövarsson², and Michael Farle¹ — ¹Fakultät für Physik and CeNIDE, Universität Duisburg-Essen, Duisburg, Germany — ²Department of Physics and Materials Science, Uppsala University, Uppsala, Sweden

Amorphous building blocks, due to their uniformity, are good candidates for TMR (tunnelling magnetoresistance) structures, for which the tailoring of magnetic anisotropy is a valuable aspect. Amorphous thin films Al/AlZr/Fe₂₄Co₆₈Zr₈(10 nm)/AlZr/Si and Al/AlZr/[Fe₂₄Co₆₈Zr₈(3 nm)/AlZr(3 nm)]₂/Si were grown using dc magnetron sputtering in the presence of an external magnetic field (growth field). The two magnetic layers of the latter sample were deposited in different directions of the growth field rotated by 90^∘ to each other. By means of ferromagnetic resonance (FMR), a uniaxial anisotropy with the hard axis along the direction of the growth field was found in the single layer sample. The FMR spectra of the bi-layer reveal the superposition of 2 sets of angular dependences shifted by 90^∘ to each other, indicating that the growth field has imprinted layer specific anisotropy in different layers. The temperature dependences of effective magnetization and uniaxial anisotropy have been evaluated from low-temperature FMR. The hysteresis loops of the single layer sample measured by SQUID show exchange bias which decreases with increasing temperature, suggesting the presence of an antiferromagnetic phase in the sample. Supported by DFG/SFB 491.