  Epitaxial thin films of hexagonal ErMnO3 fabricated on Pt(111)/Al2O3(0001)
and YSZ(111) substrates exhibited both ferroelectric character and magnetic
ordering at low temperatures. As the temperature was reduced, the ErMnO3 films
first showed antiferromagnetism. At lower temperatures, the films deposited at
lower oxygen partial pressures exhibited spin glass behavior. This re-entrant
spin glass behavior was attributed to competition between an antiferromagnetic
interaction in the hexagonal geometry and a ferromagnetic interaction caused by
a change in Mn valence induced by excess electrons from the oxygen vacancies.
