Abstract
The controllability over strongly correlated electronic states promises unique electronic devices. A recent example is an optically induced ultrafast switching device based on the transition between the correlated Mott insulating state and a metallic state of a transition metal dichalcogenide 1T-TaS2. However, the electronic switching has been challenging and the nature of the transition has been veiled. Here we demonstrate the nanoscale electronic manipulation of the Mott state of 1T-TaS2. The voltage pulse from a scanning tunnelling microscope switches the insulating phase locally into a metallic phase with irregularly textured domain walls in the charge density wave order inherent to this Mott state. The metallic state is revealed as a correlated phase, which is induced by the moderate reduction of electron correlation due to the charge density wave decoherence.
Highlights
The controllability over strongly correlated electronic states promises unique electronic devices
We note that the long-range charge density wave (CDW) order is lost within the textured CDW domain
Our calculations unambiguously show that the width of the subband straddling the Fermi level at U 1⁄4 0 is linearly increased by the decrease of the CDW order parameter (Supplementary Fig. 3)
Summary
Phase manipulations of the charge ordered Mott insulator. Figure 1a illustrates the CdI2-type crystal structure of 1T-TaS2 with Ta atoms octahedrally coordinated by S atoms. Our theoretical calculations based on spin-liquid physics[30] (Methods) reveals a metal–insulator transition as a function of U/t (t, an intersite hopping integral proportional to W), which captures the major experimental findings; the weakening and broadening of the Hubbard states together with the reduction of the Mott gap and the appearance of the sharp peak near EF (Fig. 3d) This peak was assigned as the coherent resonance of correlated electrons in the previous dynamic mean field theory calculations[31]. These theories assure that the present textured CDW phase is a correlated metallic state close to the critical regime of the Mott transition (U/tB1.4 in Fig. 3f and Supplementary Fig. 2). While we attribute those deviations to the interference effect caused by the tunnelling current[33,34,35], a further study on the spectral details is desirable
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