Current-perpendicular-to-plane giant magnetoresistance in spin-valve structures using epitaxial Co_2FeAl_(0.5)Si_(0.5)/Ag/Co_2FeAl_(0.5)Si_(0.5) trilayers

摘要

A current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) spin valve using epitaxial layers of Co_2FeAl_(0.5)Si_(0.5) (CFAS) Heusler alloy as ferromagnetic electrodes is reported. A multilayer stack of Cr/Ag/CFAS/Ag/CFAS/Co_(75)Fe_(25)/Ir_(22)Mn_(78)/Ru was deposited on a MgO (001) single crystal substrate. Epitaxial growth of the Cr, Ag, and CFAS layers in the (001) orientation up to the top CFAS layer was confirmed. Large MR ratios of 6.9% at room temperature and 14% at 6 K were observed for the CPP-GMR device. High spin polarization of epitaxial CFAS is the possible reason for high MR ratios.