Observation of a phase transition from theTphase to theHphase induced by a STM tip in1T−TaS2

Abstract

We have fabricated an $H\ensuremath{-}$phase ${\mathrm{TaS}}_{2}$ crystal in the surface layer of a $T\ensuremath{-}$phase ${\mathrm{TaS}}_{2}$ single crystal using a scanning tunneling microscope (STM) tip. After applying a relatively high bias voltage to the STM tip, we observed a significant change of the surface indicating the formation of the $H$ phase near the exposed region. The STM image shows the characteristic triangular phase boundary between the original $T$ phase $(\sqrt{13}\ifmmode\times\else\texttimes\fi{}\sqrt{13}$ charge-density-wave superstructure) and the newly fabricated $H$ phase (a triangular atomic lattice). Around the phase boundary, the local distortions of the $\sqrt{13}\ifmmode\times\else\texttimes\fi{}\sqrt{13}$ charge-density-wave superstructure have also been observed. The high-resolution STM image near the phase boundary suggests a sliding of the surface $S$ atomic sheet by the STM modification procedure.