Dielectric anomaly and magnetic response of epitaxial orthorhombic YMnO₃ thin films

The structure, magnetic response, and dielectric response of the grown epitaxial thin films of the orthorhombic phase of YMnO₃ oxide on Nb:SrTiO₃ (001) substrates have been measured. We have found that a substrate-induced strain produces an in-plane compression of the YMnO₃ unit cell. The magnetization versus temperature curves display a significant zero-field cooling (ZFC)-field cooling hysteresis below the Néel temperature (T_N ≈ 45 K). The dielectric constant increases gradually (up to 26%) below the T_N and mimics the ZFC magnetization curve. We argue that these effects could be a manifestation of magnetoelectric coupling in YMnO₃ thin films and that the magnetic structure of YMnO₃ can be controlled by substrate selection and/or growth conditions.