US scientists show light can move atoms in 2D semiconductors

Scientists at Rice University have demonstrated that light can physically move atoms within two-dimensional (2D) semiconductors called Janus transition metal dichalcogenides (TMDs). Using laser beams, they observed that light exerts a mechanical force—known as optostriction—on atoms inside these ultra-thin crystals, altering their symmetry and optical properties. This discovery provides new insights into light-matter interactions at the atomic scale and suggests a novel method to tune materials for advanced optical and quantum technologies. The research focused on Janus TMDs, which have asymmetric atomic layers made of different elements, creating built-in polarity and enhanced sensitivity to external stimuli like light. By shining laser light at resonant frequencies on a two-layer Janus TMD composed of molybdenum sulfur selenide stacked on molybdenum disulfide, the team detected distortions in the material’s second harmonic generation (SHG) pattern—a signature of atomic displacement caused by light-induced forces. This sensitivity