Spatially Extended Charge Density Wave Switching by Nanoscale Local Manipulation in a VTe<sub>2</sub> Monolayer.

Chazarin, Ulysse; Lezoualc'h, Mahé; Karn, Abhishek; Chou, Jyh-Ping; Pai, Woei Wu; Chacon, Cyril; Girard, Yann; Repain, Vincent et al. · Nano Lett · 2024

basic_science · Level V

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Abstract

Monolayer transition metal dichalcogenide VTe<sub>2</sub> exhibits multiple charge density wave (CDW) phases, mainly (4 × 4) and (4 × 1). Here we report facile dynamic and tens-of-nanometer scale switching between these CDW phases with gentle bias pulses in scanning tunneling microscopy. Bias pulses purposely stimulate a reversible random CDW symmetry change between the isotropic (4 × 4) and anisotropic (4 × 1) CDWs, as well as CDW phase slips and rotation. The switching threshold of ∼1.0 V is independent of bias polarity, and the switching rate varies linearly with the tunneling current. Density functional theory calculations indicate that a coherent CDW phase switching incurs an energy barrier of ∼2.0-3.0 eV per (4 × 4) unit cell. While there is a challenge in understanding the observed large-area CDW random fluttering, we provide some possible explanations. The ability to manipulate electronic CDW phases sheds new light on tailoring CDW properties on demand.