Relationship between film structure and exchange coupling in MnIr/NiFe films

Exchange couplings between MnIr antiferromagnetic layers and NiFe magnetic layers have been investigated in Hf (8 nm)/MnIr (16 nm)/NiFe (5 nm)/Hf (7 nm)/Si(10 0) films formed by ion-beam sputtering. When the acceleration voltage of the ion gun was higher than 600 V and the ion current was 50–100 mA, the FCC-(1 1 1) texture of the MnIr layer became strong and the MnIr crystallites were relatively large. The large crystallites caused strong exchange couplings between the MnIr layers and the NiFe layers. The highest exchange bias field was 14.8 kA/m. A Ta (7 nm)/MnIr (14 nm)/NiFe (5 nm)/Ta (6 nm)/Si(1 0 0) film was also prepared by RF sputtering. The RF-sputtered film had the larger crystallites than the ion-beam-sputtered films. The exchange bias field was 23.1 kA/m.