  Magneto-optic studies of ZnO doped with transition metals Co, Mn, V and Ti
indicate a significant magnetic circular dichroism (MCD) at the ZnO band edge
at room temperature, together with an associated dispersive Faraday rotation.
Similar spectra occur for each dopant which implies that the ferromagnetism is
an intrinsic property of the bulk ZnO lattice. At 10 K additional paramagnetic
contributions to the MCD are observed, but above about 150K, the magnitude of
the MCD signal is dominated by the ferromagnetism and is almost temperature
independent. The MCD at the ZnO band edge shows room temperature hysteretic
behaviour.
