Low-Frequency Noise Spectroscopy of the Charge-Density-Wave Phase Transitions in Vertical Tantalum Disulfide Devices*

Noise spectroscopy has proven itself as an effective tool for investigating the phase transitions in two-dimensional (2D) charge density wave (CDW) materials [1]. Almost all studies of CDW effects in 2D systems focused on transport along the atomic planes. Here we report results of investigation of CDW transitions in vertical 1T-TaS₂ devices. We observed two jumps in electrical resistivity – at the temperature range from 150 K to 180 K, and another at 80 K to 85 K. The low-frequency noise spectral density, revealed strong peaks at these transition points, sometimes changing by as much as three orders-of-magnitude. The higher temperature feature can be associated with the transition between the commensurate and nearly commensurate CDW states. The lower temperature transition can indicate the debated “hidden” CDW phase. The obtained results are important for the proposed applications of vertical van der Waals heterostructures in memory and logic gates.
[1] G. Liu, et. al., "Low-frequency current fluctuations and sliding of the charge density waves in 2D materials," Nano Lett., 18, 3630 (2018).