Spontaneous polarization and bulk photovoltaic effect (BPVE) are two concomitant physical properties in ferroelectric materials. The flipping of ferroelectric order usually accompanies with the switching of BPVE as both of them are reversed under the inversion symmetry. In this study, we report the distinctive BPVE characters in two-dimensional (2D) interlayer sliding ferroelectric materials featuring unswitchable in-plane BPVE (light-induced photocurrent in the xy plane) and switchable out-of-plane BPVE (light-induced polarization along the z-direction). Symmetry analysis within abstract bilayer crystal model and first-principles calculations validate these BPVE properties. It is because the positive and negative ferroelectric states caused by interlayer sliding are related by mirror symmetry which cannot flip all the BPVE tensor elements. This finding extends the understanding of the relationship between ferroelectricity and BPVE. On one hand, the switchable out-of-plane BPVE can be used to design switchable photoelectric devices. On the other hand, the in-plane BPVE is robust against the ferroelectric flipping, and the unswitchable character is beneficial to construct larger-scale photoelectric devices.
Tip-Based Proximity Ferroelectric Switching and Piezoelectric Response in Wurtzite Multilayers
Frantsevich Institute for Problems in Materials Science, National Academy of Sciences of Ukraine（乌克兰国家科学院弗拉特谢维奇材料科学问题研究所）；Institute of Physics, National Academy of Sciences of Ukraine（乌克兰国家科学院物理研究所）；Department of Materials Science and Engineering, University of Tennessee（田纳西大学材料科学与工程系）；Department of Materials Science and Engineering, Pennsylvania State University（宾夕法尼亚州立大学材料科学与工程系）
Machine-learning-identified two-dimensional van der Waals multiferroics for four-state nonvolatile memory
College of Physics and Optoelectronic Engineering, Shenzhen University（深圳大学物理与光电工程学院）；International School of Microelectronics, Dongguan University of Technology（东莞理工学院微电子学院）
