Hidden magnetism in the paramagnetic phase of EuTiO₃.

EuTiO3 is investigated experimentally by temperature dependent conductivity and dielectric constant measurements. Both data sets evidence a crossover behavior in their temperature dependence around T * ~ 200 K indicating a change of the electrical and magnetic behavior of EuTiO3 as already observed by muon spin rotation (μSR) measurements. Around T '  =  80 K an additional anomaly appears which is consistent with previous resonant ultrasound spectroscopy (RUS) data. By applying a magnetic field (1.2 T at room temperature) the bulk conductivity is anomalously enhanced by more than one order of magnitude. The bulk dielectric constant ε(r) decreases with increasing temperature and is enhanced by the magnetic field by up to 22%. All data reveal a substantial hysteresis which is diminished in a magnetic field. The unusual magnetic field dependence of all quantities is suggested to stem from magnetically active domain walls which are mobile between the structural phase transition temperature (T(S)  =  282 K) and T * and are pinned below it.