Static and dynamic magnetic properties in exchange-biased NiFe/FeMn multilayers

Abstract

In this work, NiFe(15 nm)/FeMn(t AF ) exchange-biased multilayers are fabricated by magnetron sputtering. The static magnetic properties are characterized using a vibrating sample magnetometer, while the dynamic properties are measured by a vector network analyzer in the frequency range of 0.2–5 GHz. The discrepancy between static and dynamic magnetic anisotropies, especially in the case of thin FeMn layers, for example t AF = 3 nm, can be explained by the rotational anisotropy (H rot ). Compared with the exchange-biased bilayers, the [NiFe(15 nm)/FeMn(t AF )]2 multilayers show a larger resonance frequency (f FMR) and effective damping coefficient (α eff ). Through analysis of the static $$\left( {H_{K}^{sta} } \right)$$ and dynamic $$\left( {H_{ \, K}^{dyn} } \right)$$ anisotropy fields in each NiFe layer, we find that H rot in the up NiFe layer is much larger than that in the down one.