Dresden 2006 – wissenschaftliches Programm
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MA: Magnetismus
MA 20: Poster: Films(1-36) Transp(37-56) Ex.Bias(57-67) Spindyn(68-80) Micromag(81-95) Particle(96-109) Imag.+Surface(110-113) Spinelectr(114-122) Theory+Micromag(123-131) Spinstr+Aniso(132-142) MagMat(143-156) Meas(157,158) MolMag+Kondo(159-162) Postdead(163-)
MA 20.56: Poster
Dienstag, 28. März 2006, 15:15–19:15, P1
Magnetoresistance of tunnel junctions with electrodes of the Heusler compounds Co2MnGe and Co2MnSn — •Verduijn Erik and Kurt Westerholt — Institut für Experimentalphysik/Festkörperphysik, Ruhr-Universität Bochum, 44780 Bochum, Germany
Heusler compounds with predicted 100% spin polarization at the Fermi level are materials of great potential in the field of spintronics. We have fabricated magnetic tunnel junction using the fully spin polarized Heusler compounds Co2MnGe and Co2MnSn as the bottom electrode and Co as the counter electrode. The films are patterned using shadow mask technique and the Al2O3 tunnel barrier is prepared by plasma oxidation of a thin Al layer. The tunnel magnetoresistance which we determine at low temperatures is 27% maximum, corresponding to a spin polarization much lower than the theoretically predicted 100%. We discuss the origin of the loss of full spin polarization, which could be caused by some oxidation of the Heusler surface at the Heusler/barrier interface, or the loss of half metallicity for a surface layer of the Heusler compound due to by site disorder or interdiffusion.
The authors thank the DFG for financial support of this work within the SFB 491 Bochum/Duisburg.