Observation of Ferroelectric Hysteresis Loop of Fe₃O₄ at 4.2 K

The existence of ferroelectricity in magnetite has been established by determining the c -axis component of the spontaneous polarization at 4.2 K. The ferroelectric D - E hysteresis loop was observed by changing the applied electric field stepwise by 5 kV/cm at intervals of 10 s between -15 kV/cm and 15 kV/cm. It has been found that, at 4.2 K, the coercive field is extremely high and the electric leakage current is still prominent. The switching process of the polarization was observed at the d c field of 20 kV/cm.