Inverse magnetoresistance in the simple spin-valve system Fe1-xVx/Au/Co

Origin of step-like behavior in the Co/Si system

A systematic investigation of the structure, nature of the interface and their possible connections with magnetic properties for the as-deposited Co/Si/Co trilayer system has been carried out. X-ray reflectivity, cross-sectional transmission electron microscopy and x-ray emission measurements performed on the Co/Si/Co trilayer system show that when the Si layer thickness is less than ∼ 20 Å, the full Si layer is converted into a cobalt silicide layer whereas when the Si layer thickness > 20 Å along with the silicide layer. the pure Si layer also remains. A comparison of magneto-optical Kerr effect and magnetoresistance measurements reveals the absence of antiferromagnetic coupling in these samples. Double-step-like magnetization, in the case of Si layer thickness > 20 Å between two Co layers, is explained by magnetization reversal of two ferromagnetic layers having different coercivities, independent of each other.

Direct experimental evidence for the Ruderman-Kittel-Kasuya-Yosida interaction in rare-earth metals

We show that the ferromagnetic heavy rare-earth (RE) metals show a transport spin polarization at the Fermi level in the majority spin, whereas in ferromagnetic light rare earths it is in the minority spin. The sign of the polarization is in agreement with what is expected due to the Ruderman-Kittel-Kasuya-Yosida (RKKY) coupling formalism. We show that magnetotransport measurements on magnetic multilayer samples containing magnetic REs provide a unique opportunity to verify the RKKY coupling scheme in pure rare-earth metals, allowing us to probe both the sign and temperature dependence of the spin-density oscillation.