  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.
