Highly spin-polarized tunneling in fully epitaxial Co2Cr0.6Fe0.4Al∕MgO∕Co50Fe50 magnetic tunnel junctions with exchange biasing

Abstract

Fully epitaxial magnetic tunnel junctions (MTJs) with exchange biasing were fabricated with a full-Heusler alloy Co2Cr0.6Fe0.4Al (CCFA) thin film and a MgO tunnel barrier, where a Co50Fe50 upper electrode was used in a synthetic ferrimagnetic Co50Fe50∕Ru∕Co90Fe10 trilayer exchange-biased with an IrMn layer through the Co90Fe10∕IrMn interface. The fabricated MTJs exhibited clear exchange-biased tunnel magnetoresistance (TMR) characteristics with high TMR ratios of 109% at room temperature and 317% at 4.2K. A high tunneling spin polarization of 0.88 at 4.2K was estimated for epitaxial CCFA films with the B2 structure.