Large Anisotropic Magnetoresistance Of Ruthenium-Based Heusler Alloys

Anomalous magnetic behavior was found in the polycrystalline Heusler alloy system Ru2Mn1-xFexGe. Samples of x=0 and 1.0 show no magnetoresistance (MR); however, the anisotropic MR effect is observed for x=0.5 (MR ratios of -4% and +2% are observed under parallel and perpendicular configurations of applied field and applied current, respectively). Moreover, magnetic measurement revealed that the sample of x=0 is antiferromagnetic, whereas the samples of x=0.5 and 1.0 are ferromagnetic with Curie temperatures of 270 and 490 K, respectively. The saturation magnetization and coercivity at 5 K are 3.1 mu(B)/f.u. and negligibly small for x=1.0 and 1.8 mu(B)/f.u. and 0.1 T for x=0.5, respectively. The MR effect is explained by a model in which antiferromagnetic and ferromagnetic domains coexist. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3080561]