Ferroelectricity and ferrimagnetism of hexagonal YbFeO₃ thin films

The coexistence of ferroelectricity and magnetic order in epitaxial hexagonal YbFeO₃ (h-YbFeO₃) thin films deposited on yttria stabilized zirconia substrates is examined using an impedance analyzer, a second harmonic generation (SHG) microscope, an X-ray diffractometer, a transmission electron microscope and a superconducting quantum interference device magnetometer. The results show that h-YbFeO₃ films exhibit ferroelectricity below 350K with threefold translational periodicity along the [110] direction similar to rare earth manganese oxides, and ferrimagnetism with a four-up and two-down spin configuration of Fe⁺³ and Yb⁺³ ions along the c-axis at low temperatures. In addition, a possibility of new ferroelectric phases with an electronic origin induced by the magnetic ordering is discussed based upon SHG and D-E hysteresis measurements.