CHARGE-DENSITY WAVES OF 1T-TAS2 IMAGED BY ATOMIC FORCE MICROSCOPY

The layer-structure transition-metal dichalcogenide 1T-TaS2 has been imaged in air at room temperature by atomic force microscopy (AFM). The images reveal both the atomic lattice and the periodic lattice distortion (PLD) associated with the charge density wave. The PLD period, orientation relative to the atomic lattice, and amplitude all agree with diffraction measurements. Under different imaging conditions the PLD can appear with a large amount of disorder or as a near-perfect superlattice. This difference is attributed to the tip-sample interaction. Simultaneous force and current images are shown that demonstrate the different imaging mechanisms of scanning tunneling microscopy and AFM.