Ferroelectric and magnetic properties in ϵ -Fe₂O₃epitaxial film

The phase stability, ferroelectricity, and magnetism of highly crystalline epitaxial ϵ-Fe2O3 films deposited on SrTiO3(111) substrates are reported. Temperature-dependent x-ray diffraction measurements revealed that α-Fe2O3 appeared as a secondary phase after samples were annealed up to 1000 °C. A clear saturated and opened polarization-electric field hysteresis loop with the remnant polarization ∼2.6 μC cm-2 and coercive electric field ∼100 kV cm-1 was obtained at room temperature using a conventional ferroelectric measurement technique. The magnetic phase transition was observed at 155 K. Magnetization-magnetic field measurements revealed that magnetic softening via the phase transition accompanied a reduction in the coercive field from 10 to 6.8 kOe, which is smaller than the coercive field reduction previously observed for ϵ-Fe2O3 nanoparticles.