Temperature effect on anisotropies in [001] Co-NiMn thin films

We have studied the temperature effect on magnetic properties in [001] epitaxial Co-NiMn. The interfacial exchange coupling in Co-NiMn not only induces a unidirectional anisotropy but also a uniaxial anisotropy. Double shifted hysteresis loops could be found along the hard axis, and used to accurately determine the anisotropy constants using the coherent rotation model. The cubic anisotropy of Co decreases monotonically with increasing temperature, while the interface-induced uniaxial anisotropy decreases with increasing temperature up to 180°C, and then increases with further increasing temperature. A mechanism explaining the enhancement of interface-induced uniaxial anisotropy and coercivity at temperatures above 180°C is proposed.