Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208016, India.
Phys Rev Lett. 2013 Aug 23;111(8):087601. doi: 10.1103/PhysRevLett.111.087601. Epub 2013 Aug 21.
We demonstrate room temperature ferroelectricity in the epitaxial thin films of magnetoelectric gallium ferrite. Piezoforce measurements show a 180° phase shift of piezoresponse upon switching the electric field indicating nanoscale ferroelectricity in the thin films. Further, temperature-dependent impedance analysis with and without the presence of an external magnetic field clearly reveals a pronounced magnetodielectric effect across the magnetic transition temperature. In addition, our first principles calculations show that Fe ions are not only responsible for ferrimagnetism as observed earlier but also give rise to the observed ferroelectricity, making gallium ferrite a unique single phase multiferroic.
我们在磁电镓铁氧体的外延薄膜中展示了室温铁电性。压电力测量显示，在电场切换时压电阻抗响应发生 180°相移，表明薄膜中存在纳米级铁电性。此外，在存在和不存在外加磁场的情况下，随温度变化的阻抗分析清楚地揭示了在磁性转变温度处明显的磁电致伸缩效应。此外，我们的第一性原理计算表明，Fe 离子不仅像以前观察到的那样负责亚铁磁性，而且还导致了观察到的铁电性，使镓铁氧体成为一种独特的单相多铁性材料。
