Magnetodielectric and dielectric properties of orthorhombic HoMnO3 thin films

Sandwich-structural multilayer films Au/HoMnO3/YBa2Cu3O7 − δ were prepared epitaxially on SrTiO3 (001) single crystal substrates by using pulsed laser deposition technique. The HoMnO3 films crystallized in a metastable orthorhombic structure and the Au and YBa2Cu3O7 − δ were used as electrodes to investigate the dielectric and magnetodielectric properties of HoMnO3 films. The impedance and electric modulus spectroscopic plots were used to discern the intrinsic characteristics of HoMnO3 films or unwanted interface effects. The low-temperature (~ 2 K) dependence of the dielectric constant of HoMnO3 films as function of frequency shows anomalies around 43 K and 22 K, which is corresponding to the Néel temperature and lock-in transition of Mn3+ moments, respectively. The magnetodielectric effects of HoMnO3 films were investigated at 100 kHz under a 2T applied magnetic field, and the dielectric constant was tuned resulting in a decrease of 3%. The results indicate the strong coupling between the dielectric properties and magnetic orders in orthorhombic HoMnO3 films.