Assessing interface coupling in exchange-biased systems via in-field interaction plots.

An in-field interaction plot, $\delta M_{\rm R}$, has been recently introduced, presenting important advantages over the classical remanence plots. Here a general $\delta M_{\rm R}$ is proposed, allowing to assess interactions even in systems with shifted and asymmetric major loops. To construct such a plot, a recoil loop and the position of the center of the major loop are only needed. Applying the method on exchange-biased Co/IrMn bilayer gives two types of $\delta M_{\rm R}$ obtained for measuring field either parallel or antiparallel to the exchange-bias direction. This provides valuable information on the reversal mechanism and allows distinguishing between effects coming from magnetic coupling into the ferromagnet (Co) and those stemming from interactions in its interface with the antiferromagnet (IrMn). The essentially nonzero general $\delta M_{\rm R}$ plot obtained from the major loop revealed to be a precise measure of the reversal asymmetry. The technique can readily be adjusted for use in other scientific fields where hysteresis is observed. We provide free software which generates such $\delta M_{\rm R}$ plot(s).