Magnetization dynamics of coupled ferromagnetic-antiferromagnetic thin films

Abstract

The existence of mixed magnetic anisotropies and a systematic modification of the dynamic damping parameter in ferromagnet/ antiferromagnet polycrystalline thin film systems as a function of antiferromagnetic layer thickness is demonstrated. Independent of the existence of exchange bias, using ultra-thin antiferromagnet layers, a controlled adjustment of static and dynamic magnetic properties of ferromagnetic thin films is achieved. Due to the combined increase of precessional frequency and effective damping parameter, a significant reduction in magnetic relaxation time is achieved. Simple relations based on the assumption of an interfacial antiferromagnetic layer contribution are derived. The addition of thin antiferromagnetic layers in contact to ferromagnetic thin films facilitates for controlled alteration of magnetic properties beyond the established manipulation of the intrinsic ferromagnetic material properties. The experimental findings are of great importance from a fundamental point of view and are significant for various applications based on ferromagnetic thin film technology. © 2009 Springer-Verlag Berlin Heidelberg.