Magnetic proximity effects in antiferromagnet/ferromagnet bilayers: the impact on the Néel temperature.

We present a study of the ordering temperature of an ultrathin antiferromagnetic film in the proximity of a ferromagnetic layer. The Néel temperature of a single-crystalline antiferromagnetic FexMn1-x film on Cu(001) in contact with a ferromagnetic Ni layer was monitored by the discontinuity in the coercivity as a function of temperature by magneto-optical Kerr effect measurements. It decreases by up to 60 K if the magnetization axis of the ferromagnet is switched from out of plane to in plane by deposition of a Co overlayer. These results give clear evidence for a magnetic proximity effect in which the ferromagnetic layer substantially influences the ordering temperature of the antiferromagnetic layer.