Berlin 2008 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 10: Magnetic Materials

MA 10.4: Vortrag

Montag, 25. Februar 2008, 16:00–16:15, H 1028

Simultaneous magnetoresistance measurements and Kerr microscopy of iron whiskers — •Michael Kirsch, Ivo Knittel, and Uwe Hartmann — Institute of Experimental Physics, Saarland University, P.O.Box 151150, D-66041

Measurements of magnetoresistance and (giant) magnetoimpedance of single crystals have been carried out at room temperature as a function of applied longitudinal magnetic field, current amplitude and current frequency. Simultaneously, the magnetic surface domain structure of the probes was imaged by Kerr microscopy (MOKE). Iron whiskers of 70 to 105 micrometer in diameter with <100> and <111> growing directions have been used for the experiments. Crystallography, zero-field domain structure and MOKE imaging properties will be discussed in detail. The correlation between circumferential magnetic permeability, magnetoimpedance and magnetoresistive effects is discussed on the basis of MOKE and resistivity data. The results permit to model changes of the domain structure during the magnetoimpedance measurement. Magnetoimpedance in iron whiskers can be understood in close analogy to the "giant magnetoimpedance" known from amorphous wires with a "bamboo" domain structure.