Atomic Lattice Disorder in Charge Density Wave Phases of Exfoliated Dichalcogenides (1T-TaS2)

Abstract

Charge density waves (CDW) and their concomitant periodic lattice distortions (PLD) govern the electronic properties in many layered transition-metal dichalcogenides. In particular, 1T-TaS2 undergoes a metal-to-insulator phase transition as the PLD becomes commensurate with the crystal lattice. Here we directly image PLDs of the nearly-commensurate (NC) and commensurate (C) phases in thin exfoliated 1T-TaS2 using atomic resolution scanning transmission electron microscopy at room and cryogenic temperature. At low temperatures, we observe commensurate PLD superstructures, suggesting ordering of the CDWs both in- and out-of-plane. In addition, we discover stacking transitions in the atomic lattice that occur via one bond length shifts. Interestingly, the NC PLDs exist inside both the stacking domains and their boundaries. Transitions in stacking order are expected to create fractional shifts in the CDW between layers and may be another route to manipulate electronic phases in layered dichalcogenides.

4 figures in Proceedings of the National Academy of Sciences of the United States of America, 2016

References in corpus (3)

• Gate-tunable Phase Transitions in 1T-TaS${}_2$
• Gate-tunable Memristive Phenonmena Mediated by Grain Boundaries in Single Layer MoS2
• Pressure dependence of the charge density wave in 1T-TaS2 and its relation to superconductivity

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