Multiferroicity around Verwey transition in Fe3O4 thin films

We report observation of finite remanent polarization (∼10-80 nC/cm2) and reasonably strong magnetoelectric coupling in thin film of Fe3O4 within a temperature range from ∼40 K to Verwey transition temperature TCO ∼120 K. Both the intrinsic capacitance and remanent ferroelectric polarization decrease by ∼20-60% under 0-50 kOe field within this temperature range. The measurements using conventional techniques do not yield convincing results as the ferroelectric polarization is small and loss is large. However, use of more sophisticated protocol - which eliminates the contribution from loss and nonhysteretic polarization effectively - provides reliable information about remanent polarization and its change under magnetic field around the Verwey transition.