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MA: Fachverband Magnetismus

MA 32: Magnetic Thin Films III

MA 32.9: Vortrag

Donnerstag, 26. März 2009, 12:15–12:30, HSZ 403

Damping by slow relaxing rare earth impurities in Ni₈₀Fe₂₀ — •Matthias Kiessling¹, Georg Woltersdorf¹, Gereon Meyer², Jan-Ulrich Thiele², and Christian H. Back¹ — ¹University of Regensburg, 93040 Regensburg, Germany — ²San Jose Research Center, Hitachi Global Storage Technologies 650 Harry Road, San Jose, CA 95120, U.S.A

The relaxation of the magnetization in soft ferromagnetic Ni₈₀Fe₂₀ films can be efficiently controlled by rare earth (RE) dopants. We investigate the frequency and temperature dependence of the ferromagnetic resonance (FMR) linewidth of Ni₈₀Fe₂₀ films doped with various RE elements of different concentrations. The central lanthanides Terbium, Dysprosium and Holmium give rise to a large increase of the damping even at very low doping levels. A Terbium concentration of only 2% leads for example to a broadening of the FMR linewidth by a factor of 50 compared to a pure NiFe film.

By means of ferromagnetic resonance measurements performed over a wide frequency (0.1-35 GHz) and temperature (20-350K) range the origin of the RE induced damping was identified. It can be concluded that the slow relaxing impurity mechanism is responsible for the relaxation observed in the RE intermetallic alloy films.