Large anomalous enhancement of perpendicular exchange bias by introduction of a nonmagnetic spacer between the ferromagnetic and antiferromagnetic layers

This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.In (Pt/Co)n/FeMnmultilayers, the magnitude of exchange bias,HE, can be considerably enhanced by placing an ultrathin nonmagnetic Pt spacer between the multilayer (ML) and the antiferromagnetic(AFM) layer. The bias is maximum for a spacer layer thickness, t, of a few angstroms and it decreases progressively as t is further increased. This bias enhancement is accompanied by an increase of coercivity,HC. This behavior is due to the role of the Pt spacer in enhancing the perpendicular effective anisotropy of the last Co layer in the ML, which has the effect of increasing the net ferromagnetic (FM)/AFM spin projection, thus leading to the HE and HC enhancements. The decrease of HE and HC for thicker spacer layers is due to the limited range of the FM-AFM proximity effect