Enhancement of spin-asymmetry by L2_1-ordering in Co_2MnSi/Cr/Co_2MnSi current-perpendicular-to-plane magnetoresistance devices

摘要

Co_2MnSi/Cr/Co_2MnSi (OOl)-fully epitaxial current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) devices were fabricated via an UHV magnetron sputtering system. The relationship between the degree of chemical ordering in Co_2MnSi (CMS) and the CPP-GMR characteristics was investigated systematically against the annealing temperature of the devices. X-ray diffraction profiles and reflection high-energy electron diffraction images indicated that annealing improved L2_1-ordering. The MR ratio also increased upon annealing and the maximum MR ratio of 5.2% and ΔRA of 6.5 mΩ μm~2 were achieved by annealing at 400 ℃. These results indicate that promoting the degree of L2_1 -ordering in CMS enhances the bulk and/or interface spin-asymmetry coefficients.