Effect of antiferromagnetic thickness on thermal stability of static and dynamic magnetization of NiFe/FeMn multilayers

The influence of antiferromagnetic (AF) thickness on static and dynamic magnetic properties and their thermal stability in NiFe/FeMn multilayered thin films was investigated systematically. It was found that dynamic magnetic anisotropy rises at the AF thickness lower than that of static magnetic anisotropy and exchange bias. This behavior is suggested to be due to the contribution of rotatable anisotropy arising from time-dependent rotatable part of the AF spins. It is also due to the contribution of rotatable anisotropy and exchange bias that makes the thermal stability of static and dynamic anisotropies varied with AF thickness. The temperature dependences of ferromagnetic resonance frequency, Gilbert damping factor and frequency linewidth dependent on AF thickness are also discussed in conjunction with the variations of the dynamic anisotropy and exchange bias field to provide a comprehensive picture of the physical origin of their thermal stability. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4792223]