posted on 2022-01-03, 19:39authored byZhao Guan, Yifeng Zhao, Xiaoting Wang, Ni Zhong, Xing Deng, Yunzhe Zheng, Jinjin Wang, Dongdong Xu, Ruru Ma, Fangyu Yue, Yan Cheng, Rong Huang, Pinghua Xiang, Zhongming Wei, Junhao Chu, Chungang Duan
Searching
van der Waals ferroic materials that can work under ambient
conditions is of critical importance for developing ferroic devices
at the two-dimensional limit. Here we report the experimental discovery
of electric-field-induced reversible antiferroelectric (AFE) to ferroelectric
(FE) transition at room temperature in van der Waals layered α-GeSe,
employing Raman spectroscopy, transmission electron microscopy, second-harmonic
generation, and piezoelectric force microscopy consolidated by first-principles
calculations. An orientation-dependent AFE–FE transition provides
strong evidence that the in-plane (IP) polarization vector aligns
along the armchair rather than zigzag direction in α-GeSe. In
addition, temperature-dependent Raman spectra showed that the IP polarization
could sustain up to higher than 700 K. Our findings suggest that α-GeSe,
which is also a potential ferrovalley material, could be a robust
building block for creating artificial 2D multiferroics at room temperature.