Interlayer exchange coupling and spin Hall effect through an Ir-doped Cu nonmagnetic layer

Metallic superlattices where the magnetization vectors in the adjacent ferromagnetic layers are antiferromagnetically coupled by the interlayer exchange coupling through nonmagnetic spacer layers are systems available for the systematic study on antiferromagnetic (AF) spintronics. As a candidate of nonmagnetic spacer layer material exhibiting remarkable spin Hall effect, which is essential to achieve spin-orbit torque switching, we selected the Ir-doped Cu in this study. The AF coupling for the Co/Cu95Ir5/Co was investigated, and was compared with those for the Co/Cu/Co and Co/Ir/Co. The maximum magnitude of AF-coupling strength was obtained to be 0.39 mJ/m(2) at the Cu95Ir5 thickness of about 0.75 nm. Furthermore, we found a large spin Hall angle of Cu95Ir5 in Co/Cu95Ir5 bilayers by carrying out spin Hall magnetoresistance and harmonic Hall voltage measurements, which are estimated to be 3-4%. Our experimental results clearly indicate that Cu95Ir5 is a nonmagnetic spacer layer allowing us to achieve moderately strong AF coupling and to generate appreciable spin-orbit torque via the spin Hall effect.