Dresden 2006 – scientific programme

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MA: Magnetismus

MA 27: Spin-Dynamics, Magnetization Reversal II

MA 27.11: Talk

Thursday, March 30, 2006, 12:45–13:00, HSZ 403

Dynamic magnetization behavior of nanocrystalline tape wound cores — •Sybille Flohrer¹, Rudolf Schäfer¹, Jeffrey McCord¹, Stefan Roth¹, Giselher Herzer², and Ludwig Schultz¹ — ¹IFW Dresden, Institut für Metallische Werkstoffe, 01069 Dresden — ²Vacuumschmelze GmbH & Co. KG, 63450 Hanau

The so-called excess loss is an important component of dynamic magnetization losses. It originates from localized eddy currents around moving domain walls. Therefore, observation of the dynamic magnetization process together with simultaneous loss measurement provides a useful tool to investigate excess loss. Stroboscopic Kerr-microscopy observations and loss measurements on nanocrystalline Fe₇₃Cu₁Nb₃Si₁₆B₇ tape wound cores with different strength and direction of induced anisotropy are presented. In cores with an induced anisotropy along the field direction, the correlation between excess loss, strength of the anisotropy, and measured domain wall velocity on the surface is studied. The relevance of the observed surface magnetization process for the core volume is discussed. Cores with an induced anisotropy transverse to the field direction should ideally show homogeneous magnetization rotation, preventing excess loss. However, besides homogeneous rotation, inhomogeneous rotations, wall displacement processes and domain nucleation are observed in the nanocrystalline cores, being responsible for a significant excess loss.