Measurement dependence of the exchange bias

Recently, in addition to the conventional hysteresis loop measurement, several different measurement techniques, such as ac susceptibility, ferromagnetic resonance (FMR), and Brillouin light scattering, have been used to study the unidirectional exchange coupling induced in a ferromagnetic film in proximity to an antiferromagnet. In this article, we theoretically investigate how interface exchange coupling manifests itself in different measurements. The magnetic degrees of freedom of the antiferromagnet are incorporated in this analysis. Anisotropies from hysteresis loop measurements, ac susceptibility measurements, and FMR measurements are obtained. These results show that the measured exchange anisotropies differ with measurement techniques. (C) 2000 American Institute of Physics. [S0021-8979(00)36508-2].