Abstract
An unusual enhancement of the antiferromagnetic ordering (Néel) temperature is observed in a Ni80 Fe20/Co3 O4 thin film. This significant increase of the Néel temperature indicates an exchange energy of interface spins between the ferromagnet (FM) and antiferromagnet (AF) that is significantly greater than that of spins in the bulk of the film. Exchange bias is established even when the thin film is zero field cooled. Field cooling the film sets a significantly stronger exchange coupling between the FM and AF spins at the interface with a concomitant increase in the exchange-bias field. © 2007 The American Physical Society.