2023, Unveiling Layer-dependent Interlayer Coupling and Vibrations Properties in MoTe2 under High Pressure, Physical Review B.
2023, Unveiling Layer-dependent Interlayer Coupling and Vibrations Properties in MoTe2 under High Pressure, Physical Review B.
Abstract:
Layered materials have garnered significant attention for their ability to exhibit tunable physical properties through stacking, twisted angles, and interlayer coupling. The interlayer vibrations in these materials are highly sensitive to and can be controlled by their thickness. However, the layer-dependent interlayer vibration behavior under high pressure remains unclear. Here, we investigate the layer-dependent high-pressure Raman spectroscopy of 1-5L and bulk MoTe2 up to 14 GPa pressure, and demonstrate a pressure-induced thickness-dependent interlayer vibration behavior. We observe the pressure-induced blue-shift rates of the breathing (LB) and shear (S) modes exhibit opposite strong layer-dependent behaviors, which arise from thickness-dependent interlayer coupling and restoring forces, respectively. Furthermore, we propose a pressure-dependent linear chain model (LCM) to characterize the force constants under pressure and employ a bond polarization model to explain the intensity changeover between the S and LB modes, as well as between the A1/A1g and E/Eg modes, which is attributed to the increase in interlayer Te-Te bond angle and intralayer distance between Mo and Te atomic layers, respectively. Our findings elucidate the robust thickness-dependent interlayer vibrations in MoTe2 and provide a firm foundation for exploring and characterizing interlayer coupling through pressure engineering in Van der Waals materials.
Keywords: Interlayer vibration; high pressure; layer dependent; molybdenum telluride; Raman spectrum
Link: https://link.aps.org/doi/10.1103/PhysRevB.108.155302
