The charge density wave (CDW) material 1T-TaS2 exhibits a pulse-induced insulator-to-metal transition, which shows promise for next-generation electronics such as memristive memory and neuromorphic hardware. However, the rational design of TaS2 devices is hindered by a poor understanding of the switching mechanism, the pulse-induced phase, and the influence of material defects. Here, we operate a 2-terminal TaS2 device within a scanning transmission electron microscope (STEM) at cryogenic temperature, and directly visualize the changing CDW structure with nanoscale spatial resolution and down to 300 {\mu}s temporal resolution. We show that the pulse-induced transition is driven by Joule heating, and that the pulse-induced state corresponds to nearly commensurate and incommensurate CDW phases, depending on the applied voltage amplitude. With our in operando cryo-STEM experiments, we directly correlate the CDW structure with the device resistance, and show that dislocations significantly impact device performance. This work resolves fundamental questions of resistive switching in TaS2 devices critical for engineering reliable and scalable TaS2 electronics.
@article{arxiv.2309.06406,
title = {In operando cryo-STEM of pulse-induced charge density wave switching in TaS$_2$},
author = {James L Hart and Saif Siddique and Noah Schnitzer and Stephen D. Funni and Lena F. Kourkoutis and Judy J. Cha},
journal= {arXiv preprint arXiv:2309.06406},
year = {2023}
}