Anomalous Ferromagnetism in TbMnO3 Thin Films
  Magnetometry, x-ray, and neutron scattering have been used to study the structural and magnetic properties of a TbMnO3 thin film grown on a [001] SrTiO3 substrate by pulsed laser deposition. Although bulk TbMnO3 is a low temperature antiferromagnet, magnetometry measurements indicate the presence of low temperature ferromagnetism. Depth profiling by x-ray and polarized neutron reflectometry reveals a net sample magnetization that is commensurate with the film thickness, indicating that the observed ferromagnetism is not due to an altered surface phase (such as Mn3O4), or external impurities that might give rise to an artificial magnetic signal. Instead, these results show that the ferromagnetism is an intrinsic property of the TbMnO3 film. 
B. J. Kirby, D. Kan, A. Luykx, M. Murakami, D. Kundaliya, and I.   Takeuchi