Charge Density Wave Displacement Field and Intradomain Chirality in 1T-TaS₂

The transition metal dichalcogenide, 1T-TaS₂, hosts four distinct charge density wave (CDW) states. In this work we focus on the nearly commensurate charge density wave state (NC-CDW) which lies between the higher-temperature incommensurate CDW state and low temperature commensurate CDW state. Unlike the incommensurate and commensurate CDW states, the NC-CDW state is characterized by a domain structure. Within a domain, the CDW lattice resembles, but differs slightly from, the low temperature commensurate CDW state. A phase slip in the CDW lattice occurs between neighboring CDW domains. There is a continual evolution in the domain size across the NC-CDW state with the domain size increasing with decreasing temperature.



Recent work [1,2] has uncovered an intradomain chirality to the NC-CDW state. This chirality is found in the CDW displacement field, the displacement of individual CDW maxima from their expected average location, and is believed driven by a strong coupling of the CDW state to the atomic lattice. This strong-coupling-origin of CDW chirality in 1T-TaS₂ differs from chiral CDW states in other materials where orbital-ordering drives CDW chirality. Here we present our scanning tunneling microscopy (STM) measurements on 1T-TaS₂ roughly across the NC-CDW temperature range. We detail the evolution of the domain structure and intradomain chirality. We examine possible topological defects arising in the CDW displacement field.



[1] Yu et al., “Temperature Evolution of Domains and Intradomain Chirality in 1T-TaS₂.” PRB, 108, 11421 (2023).

[2] Singh et al., “Lattice-Driven Chiral Charge Density Wave State in 1T-TaS₂,” PRB, 106, L081407 (2022).