  We have grown epitaxial thin-films of the orthorhombic phase of YMnO3 oxide
on Nb:SrTiO3(001) substrates and their structure, magnetic and dielectric
response have been measured. We have found that a substrate-induced strain
produces an in-plane compression of the YMnO3 unit cell. The
temperature-dependent magnetization curves display a significant ZFC-FC
hysteresis at temperatures below the Neel temperature (TN around 40K). The
dielectric constant increases gradually (up to 26%) below TN and mimics the ZFC
magnetization curve. We argue that these effects are a manifestation of
magnetoelectric coupling in thin films and that the magnetic structure of YMnO3
can be controlled by substrate selection.
