Exchange coupling in MBE grown MnPt/NiFe bilayers

Exchange anisotropy in MnPt(30 nm)/NiFe(5 nm) bilayers was investigated for films grown by the MBE method on MgO(001) and SrTi03(001) substrates, During the deposition, a static magnetic field of 100 Oe was applied in the film plane. In-situ reflection high-energy electron diffraction observations and ex-situ X-ray diffraction measurements revealed that the MnPt layers have chemical order and have (100) orientation which is an uncompensated plane of antiferromagnetic spin alignment. The bilayers whose MnPt layer was grown on NiFe layer were found to have an exchange anisotropy field (Hex) of 220 Oe (corresponding exchange anisotropy energy of J = 0.084 erg/cm2c) of 43 Oe, while the bilayers whose NiFe layer was grown on MnPt layer show very small Hexand a large Hc.