Dielectric anomalies in orthorhombic YMnO3 thin films

We report on the magnetodielectric characterization of orthorhombic (001) oriented YMnO3 thin films grown by PLD on Nb-doped SrTiO3. Detailed temperature, magnetic field and frequency dependent measurements are used to determine dielectric and magnetodielectric response and to analyse its origin. A dielectric peak below the Néel temperature is observed. We show that this peak signals a magnetoelectric coupling as inferred from a magnetocapacitance of about 2% at 8 T and 25 K. A careful analysis of the impedance spectroscopy allows concluding that both the dielectric peak and the measured magnetocapacitance are intrinsic properties of YMnO3. At higher temperatures (> 200 K) another dielectric feature (a strong frequency dependency and a peak in the dielectric losses) is observed, which is ascribed to the Maxwell–Wagner behaviour and thus it is not a genuine response of stoichiometric YMnO3.