A STUDY OF CHARGE-DENSITY-WAVES ASSOCIATED WITH THE PERIODIC LATTICE DISTORTION IN 1T-VSE2 USING A LOW-TEMPERATURE SCANNING TUNNELING MICROSCOPE

We have investigated the charge-density-wave (CDW) formation associate d with the periodic lattice distortion in 1T-VSe2 by using a low tempe rature scanning tunneling microscope (STM) at 4.2 K. To clarify the at omic and the superlattice structures, we used a layer etching techniqu e to fabricate a step of 1T-VSe2 with a height of approximate to 6 Ang strom and investigated the atomic structures at 4.2 K on the newly etc hed region. The measured images showed a clear isotropic 4 x 4 charge- density-wave structure which was different from the previous results o btained by Coleman et al. The high resolution STM images at 4.2 K show ed that the center of CDW was surrounded by three surface atoms from t hose images we were able to identify those atoms as Se. The surface Se atoms determined the STM pattern because of their proximity to the sc anning tip.