  Exchange bias effect is an important attribute in several device
applications. Traditionally, it is discussed as a form of exchange anisotropy
at the interface between the ferromagnetic/antiferromagnetic layers of two
distinct systems. We report here on the magnetically ordered alloys possessing
the feature of unidirectional anisotropy, which reverses its sign across a
characteristic temperature. These are admixed rare earth intermetallics,
comprising two dissimilar rare earth (RE) ions, belonging to the two different
halves of the 4f-series and imbibing the notion of ferromagnetic coupling
between the spins of all 4f-rare earth ions and that of the conduction
electrons. Magnetic moments of dissimilar RE ions in such admixed alloys,
however, get antiferromagnetically coupled and they display magnetic
compensation feature such that the field induced reversal in the orientation of
the magnetic moments of dissimilar rare earth ions happens across the
compensation temperature (Tcomp). Above a threshold field, the conduction
electron polarization also reverses its sign across Tcomp, this is argued to
correlate with the observed phase reversal in the exchange bias field.
