Magnetization dynamics as derived from magneto impedance measurements

In this work, the magnetization dynamics of soft magnetic materials is stud ied with the aid of transverse differential permeability mu(I-ac,f,H-dc) sp ectra. Contributions to the magnetization processes from domain wall motion and rotation of the magnetization can be extracted from the transverse dif ferential permeability data which are in turn obtained from impedance Z(I-a c,f,H-dc) spectra. In particular, an iteration method is used to extract mu (I-ac,f,H-dc) from Z(I-ac,f,H-dc) data. The approach is tested in samples w ith a very well known domain structure, namely (110)[001]FeSi3%. Permeabili ty spectra mu(I-ac,f,H-dc) were obtained in the frequency range (100 Hz les s than or equal to f less than or equal to 100 kHz), probe current range (0 .1 less than or equal to I(ac)less than or equal to 50 mA) and dc magnetizi ng field range (0 less than or equal to H(dc)less than or equal to 500 Oe). It is shown that the method developed in this article can be efficiently u sed to identify and study different dynamic processes driven by the probe c urrent and controlled by the external dc field. In particular, it is shown that the method provides the tools to separate the reversible and irreversi ble parts of these processes. (C) 2000 American Institute of Physics. [S002 1-8979(00)05213-0].