On the field dependence of the interface energy in AF/FM bilayers

Abstract

In the investigations of antiferromagnetic (AF)/ ferromagnetic (FM) bilayer samples, often distinct experimental techniques yield different values for the measured exchange anisotropy field (H E ). We propose that the observed discrepancy may be accounted in part by the dependence of the unidirectional anisotropy with the value of the external applied field (h). Using a simple microscopic model for representing the AF/FM interface, which incorporates the effect of interface roughness, we show that the interface energy between the AF and FM layer indeed varies with h, as recently observed in anisotropic magnetoresistance measurements, lending support to our proposal. Keywords: exchange bias, unidirectional anisotropy, magnetic bilayer PACS: 75.70Cn; 75.30Gw; 75.50.Lk i j i ij J J J J