  Quantum states of strongly correlated electrons are of prime importance to
understand exotic properties of condensed matter systems and the
controllability over those states promises unique electronic devices such as a
Mott memory. As a recent example, a ultrafast switching device was demonstrated
using the transition between the correlated Mott insulating state and a
hidden-order metallic state of a layered transition metal dichalcogenides
1T-TaS2. However, the origin of the hidden metallic state was not clear and
only the macroscopic switching by laser pulse and carrier injection was
reported. Here, we demonstrate the nanoscale manipulation of the Mott
insulating state of 1T-TaS2. The electron pulse from a scanning tunneling
microscope switches the insulating phase locally into a metallic phase which is
textured with irregular domain walls in the charge density wave (CDW) order
inherent to this Mott state. The metallic state is a novel correlated phase
near the Mott criticality with a coherent feature at the Fermi energy, which is
induced by the moderate reduction of electron correlation due to the
decoherence in CDW. This work paves the avenue toward novel nanoscale
electronic devices based on correlated electrons.
