Dresden 2003 – wissenschaftliches Programm

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MA: Magnetismus

MA 14: Poster: Schichten(1-31), Spinabh.Trsp.(32-47), Exch.Bias(48-54), Spindyn.(55-64), Mikromag.(65-76), Partikel(77-88), Oflmag.(89-92), Spinelektr.(93-98), Elektr.Theo.(99-103), Mikromag+PhasÜ+Aniso.(104-122), MagnMat.(123-134), Messm+Mol-Mag.(135-139), Kondo(140-151)

MA 14.41: Poster

Dienstag, 25. März 2003, 15:15–19:15, Zelt

Domain wall scattering, GMR and Lorentz magnetoresistance in high-purity single crystalline bulk iron — •D. Elefant, R. Schäfer, C. M. Schneider, and K. Weise — IFW Dresden, Helmholtzstr. 20, D01069 Dresden

The low temperature resistivity in high-purity bulk iron single crystals with residual resistance ratios RRR = 300...5700 shows resistivity changes by more than the factor 100 in small applied magnetic fields including the self field of the dc measuring current. Kerr microscopy on the purest crystal (axis orientation near 100) showed the domain structure and its developement in small magnetic fields, responsible for the large resistivity changes. The combination of the resistivity and Kerr microscopy results gives rise to state, that the resistivity jump (in our case some 100%) from the single domain state in applied longitudinal fields to the multidomain state is a GMR effect. (electron mean free path in the single domain state exceeds 100 micrometer and the dimensions of the domains range between 1...50 micrometer). Transverse oriented domains cause a very large Lorentz magnetoresistance. In coincidence with this model the temperature dependence of the resistivity is additive in the GMR dominated region and indirect proportional to T for the Lorentz magnetoresistance.