Biaxial anisotropy driven asymmetric kinked magnetization reversal in exchange-biased IrMn/NiFe bilayers

Abstract

The significant biaxial anisotropy contribution below 50 K is evidenced and identified as a cause of asymmetric “kinked” magnetization reversal behaviour and strong single cycle training effect in ion-beam sputtered IrMn/NiFe bilayers. The minor loop measurement clearly suggests that the magnetization reversal along the descending branch of the hysteresis loop takes place in two distinct steps comprising initial magnetization rotation followed by irreversible domain processes. Our experimental observations of characteristic magnetoresistance and minor loop measurements unambiguously endorse the recent theoretical prediction of Hoffmann suggesting the critical role of the symmetry of antiferromagnetic anisotropy on the reversal asymmetry and training effect.