Inverse giant magnetoresistance (invited)

Abstract

Inverse giant magnetoresistance ͑GMR͒ is obtained in multilayers alternating two ferromagnetic layers F 1 and F 2 with different asymmetry of spin scattering, ␣ 1 Ͼ1 and ␣ 2 Ͻ1. This is clearly demonstrated in the simple spin-valve system with perpendicular magnetization Fe 1Ϫx V x /Au/Co. With respect to Fe, the FeV alloys with xϭ0.18 and 0.29 exhibit an inversion of the spin scattering coefficients ͑␣ Fe Ͼ1, ␣ FeV Ͻ1͒ due to the change of the densities of states at the Fermi level. The inverse MR of FeV/Au/Co is studied as a function of FeV layer thickness and temperature and compared to calculations based on the Camley-Barnas model. The data show that the inverse GMR is due to the bulk scattering within the FeV layer, which coexists with a substantial interface scattering favoring normal GMR.

Inverse giant magnetoresistance inFe∕Cu∕Gd1−xCoxspin-valves

“…13 Therefore, the global asymmetric factor from Co and Fe layers is larger than 1.0 and no inverse GMR effect can be observed in Co/ Cu/ Fe spin valves. As the contents of Cr and V impurity in the Fe layers increase, the spin polarization P N turns more positive 9 and the ␣ is smaller than 1.0, whereas the interfacial asymmetric factor at FeV͑Cr͒ /Cu is larger than 1.0. For thin Fe alloy layers, the contribution of the interfacial scattering dominates and the global asymmetric factor from FeV is larger than 1.0 and thus the GMR ratio is positive.…”

“…The inverse GMR has been observed in many multilayers and spin valves. [4][5][6][7][8][9] The GMR effect is attributed to originate from a competition of interfacial and bulk spin-dependent scattering, both of which are strongly related to the spin polarization of ferromagnetic layers. The spin polarization P N is usually defined as ͓N͑↑͒ − N͑↓͔͒ / ͓N͑↑͒ + N͑↓͔͒, where N͑↑͒ and N͑↓͒ are the density of states ͑including s and d electrons͒ at Fermi level for majority spins and minority ones, respectively.…”

Magnetic properties of phase-separated (Ni/sub 80/Fe/sub 20/)/sub 1-x/Mn/sub x/ thin films

“…The inverse GMR effect in those materials has been attributed to the bulk spin scattering [9] and difference in the scattering cross sections [10]. It is, however, not clear about the origin of the inverse GMR in the Ni Fe Mn alloy.…”

Perpendicular and Parallel Transport, and Interlayer Exchange Coupling in Magnetic Trilayers with Extra Cap-Layers

“…[5][6][7]). The GMR vs. n cap case has not been studied so far, to our knowledge, the interesting finding about it is that then the CIP and CPP curves are no longer very distant from each other and, first of all, that for specific n cap -thicknesses (dependent also on n,) the GMR can be brought to negative values corresponding to the so-called inverse GMR [8,9]. Fig.…”