Extra large unidirectional anisotropy constant of Co–Fe/Mn–Ir bilayers with ultra-thin antiferromagnetic layer

Abstract Unidirectional anisotropy constant, JK, of Co1−xFex/Mn–Ir bilayer was investigated as a function of the Fe concentration, x. As a result, we obtained an extra large value of JK, which exceeds 0.5 erg/cm2, at x=0.3–0.4 with the ultra-thin (50–100 A) Mn–Ir layer. The blocking temperature of Co0.7Fe0.3 40 A/Mn–Ir 100 A bilayer was 290°C, which is sufficiently high for the application of spin valve giant magnetoresistive devices.