The current-induced metastable CDW heterostructure in 2D 1T-TaS2

The layered 1T-TaS2 is a showcase of electronic phases including complex charge density waves (CDWs), superconductivity, Mott insulator, and spin liquid. In addition to such thermodynamically stable phases, thermally inaccessible, persistent metastable metallic states can be induced by means of current [e.g.1]. We investigated the current-induced phase transition to the persistent metastable state by performing noise spectroscopy measurements [2]. We observed the emergence of a broadband noise at the transition, indicating the sliding motion of CDWs. Surprisingly, the dynamical property of the CDW was found to be preserved after the injection of current, although the electronic properties are significantly modified by the injection. It is likely that the CDW sheets slide to change their 3D structure, the stacking way, followed by the considerable change in electronic structure. We suggest that after the current injection, the CDW sheets stack in a metastable way that yields metallic electronic structure. Our discovery emphasizes the importance of the stacking degree of freedom, the concept of Van der Waals heterostructure, to create exotic electronic states in 2D material.
[1] M. Yoshida et al., Sci. Adv. 1, e1500606 (2015).
[2] M. Yoshida et al., Phys. Rev. B 100, 155125 (2019).