Variable Temperature Scanning Tunneling Microscope study on CDW material 2H-TaSe$_2$

As a layered quasi-2D material, 2H-TaSe$_2$ has a very rich phase diagram including a second order phase transition at 122K, a first order phase transition at 90K, and a superconductivity transition at 133mK. With our UHV Scanning Tunneling Microscope, we have performed temperature-controlled STM work to study the incommensurate and commensurate CDW phases of 2H-TaSe$_2$, from 77K to 110K. We will present temperature and tunneling bias voltage dependant topograph data, together with IV and dI/dV spectra in order to help understanding the nature of these two different CDW phases and the gapping mechanism of this material.