Mott Phase at the Surface of1T−TaSe2Observed by Scanning Tunneling Microscopy

In this Letter we report the observation, by scanning tunneling microscopy, of a Mott metal to insulator transition at the surface of $1\mathrm{T}\mathrm{\text{−}}{\mathrm{T}\mathrm{a}\mathrm{S}\mathrm{e}}_2$. Our spectroscopic data compare considerably well with previous angle-resolved photoemission spectroscopy measurements and confirm the presence of a large hysteresis related to a first order process. The local character of the tunneling spectroscopy technique allows a direct visualization of the surface symmetry and provides spectroscopic measurements on the defect-free region of the sample. It follows that the electronic localization is driven purely by the enhancement of the charge density wave amplitude which drives a bandwidth controlled metal-insulator transition.