Dynamical effect in measurement of the exchange-bias field: A consequence of the slow-relaxer mechanism

Abstract

We report on the temperature dependence of ferromagnetic resonance (FMR) measurements on NiFe/FeMn bilayer. This includes investigations about the angular distribution of the resonance, ${\text{H}}_{\text{R}}$, and that of the linewidth, $\ensuremath{\Delta}\text{H}$. By considering the domain-wall formation model, the exchange-bias field, ${\text{H}}_{\text{EB},\text{FMR}}$, is derived from the FMR measurements. The disagreements observed at low temperature between these values and the ones obtained from superconducting quantum interference device measurements, ${\text{H}}_{\text{EB},\text{SQUID}}$, are discussed. We demonstrate that the negative line shift and the maximum of the linewidth of the FMR line are both perfectly interpreted through the slow-relaxer mechanism. This enabled us to elucidate the intriguing question about the yielding to different values of the exchange-bias anisotropy by both techniques.