Dresden 2009 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 13: Poster Ia: Electron Theory (1); Magnetic Imaging (2,3); Thin Films (4-25); MSMA (26-33); Magn. Semiconductors (34-42); Magn. Half Metals and Oxides (43-60)
MA 13.21: Poster
Dienstag, 24. März 2009, 10:15–13:00, P1A
Coercivity analysis in highly anisotropic PrCo7 films — •Volker Neu1, Ajit Kumar Patra1, Stephen Collocott2, Sebastian Fähler1, and Ludwig Schultz1 — 1IFW Dresden, Institute for Metallic Materials, PO Box 270116, D-01171 Dresden, Germany — 2CSIRO Materials Science and Engineering, PO Box 218, Lindfield NSW 2070, Australia
In order to tailor the response of a magnetic material to an external magnetic field a sound understanding of the underlying magnetization process is required. For permanent magnet materials this central question culminates in understanding the origin of coercivity. The known concepts of coercivity analysis, the micromagnetic model and the global or phenomenological model are applied to a permanent magnet film based on epitaxial PrCo7. Such films possess a single orientation of the crystallographic c-axis within the film plane and a square shaped hysteresis with large coercivity. The temperature dependent coercivity is compared on one hand with the expected nucleation or depinning field based on the independently determined anisotropy constants and on the other hand is expressed as a thermally activated domain wall movement within a certain activation volume. For this, the fluctuation field as a function of temperature is extracted from magnetization relaxation and irreversible susceptibility measurements. A consistent description of the data is possible under the assumption of weak pinning. The analysis is however complicated by the spin reorientation from uniaxial anisotropy at high temperature to an easy-cone anisotropy below 110K.