Tailoring geometric phases of two-dimensional functional materials under light: a brief review

Information storage relies on the fast and reversible memory devices, which can read and write data easily with low energy input. In addition, in order to pursue high data storage density and miniaturizing device size, low-dimensional materials with large area to volume ratio would be preferable. Up to date, there are already a lot of explorations of two-dimensional functional material based devices with interesting phase transitions. According to Ginzburg-Landau theory, phase transition occurs when order parameter changes, under external stimuli such as temperature, electric field, or external stress. Other than these, novel phase transition mechanisms under low-frequency light irradiation has been recently proposed. The light frequency is below the corresponding energy bandgap of the semiconductors, which intuitively has very small scattering cross sections. However, according to thermodynamic theory, there could have light-matter interactions. Geometric structure can be changed and manipulated under light illumination. If ion displacements are strong enough, phase transition could occur. This optically driven phase transition approach requires no direct contacts with the sample, so that this procedure is easily controlled. In this mini-review, we briefly summarize the basic theory, computational predictions and some very recent experiments on low-frequency light induced phase transition in various systems.