  Cation displacements, oxygen octahedral tilts, and magnetism of epitaxial,
ferrimagnetic, insulating GdTiO3 films sandwiched between cubic SrTiO3 layers
are studied using scanning transmission electron microscopy and magnetization
measurements. With decreasing GdTiO3 film thickness, structural (GdFeO3-type)
distortions are reduced, concomitant with a reduction in the Curie temperature.
Ferromagnetism persists to smaller deviations from the cubic perovskite
structure than is the case for the bulk rare earth titanates. The results
indicate that the FM ground state is controlled by the narrow bandwidth,
exchange and orbital ordering, and only to second order depends on amount of
the GdFeO3-type distortion.
