The structural and magnetic properties of MnBi and exchange coupled MnBi/Fe films

The structural and magnetic properties of MnBi and MnBi/Fe films prepared by magnetron sputtering and in situ vacuum annealing are investigated. MnBi film is highly c-axis textured with perpendicular anisotropy. The out-of-plane coercivity increases with temperature, which reaches to 15kOe and 21kOe at 300K and 400K, respectively. For exchange coupled MnBi/Fe films, when the thickness of Fe layer is thin, the hysteresis loops show single-phase-like reversal behavior due to the effective interfacial exchange coupling. In comparison with MnBi film, the remanent magnetization enhances. The maximum energy product also improves from 7.6MGOe to 8.0MGOe at 300K, and from 5.7MGOe to 6.1MGOe at 400K. As the thickness of Fe layer exceeds the critical dimension, the two-step reversal behavior is observed, indicating the decoupling of soft Fe layer and neighboring hard MnBi layer.