Temperature Dependence of the Charge-Density-Wave Depinning in Quasi-2D 1T-TaS₂/h-BN Heterostructures

The 1T polymorph of TaS₂ is one of the 2D materials that reveal several charge-density-wave (CDW) phase transitions in the form of resistivity changes and hysteresis. The CDW phase is a periodic modulation of the electronic charge density, accompanied by distortions in the underlying crystal lattice, and it may be commensurate, nearly commensurate, or incommensurate with the underlying crystal lattice [1]. Since the commensurate and nearly-commensurate CDWs are locked to the lattice, there is a large energy barrier to translating the CDW across the lattice. Therefore, it was generally believed that the depinning and sliding of CDW could only occur in the incommensurate phase. However, in some materials, I-V measurements have shown depinning and sliding below the C-CDW transition temperature. We demonstrated that the CDW depinning in 2D CDW materials is substantially different from that in “conventional” CDW materials with quasi-1D crystal structures [2]. We discuss the temperature dependence of the depinning threshold in quasi-2D 1T-TaS₂/h-BN heterostructures. The depinning point was determined as the onset of current instabilities revealed from the differential I-V characteristics. The obtained results are expected to increase the functionality of 2D CDW devices.