Domain size effects on the dynamics of a charge density wave in 1T-TaS2

TL;DR

This study investigates how the size of photoinduced charge density wave domains in 1T-TaS2 affects their growth and stability, revealing anisotropic growth patterns and size-dependent lattice stability through time-resolved x-ray diffraction.

Contribution

It provides new insights into the size-dependent dynamics of photoinduced charge density waves in layered materials, using a novel double pump experimental approach.

Findings

Domains grow self-similarly with unchanged shape.

Larger amplitude modes are observed in smaller domains.

Incommensurate lattice distortion is less stable in smaller domains.

Abstract

Recent experiments have shown that the high temperature incommensurate (I) charge density wave (CDW) phase of 1T-TaS2 can be photoinduced from the lower temperature, nearly commensurate (NC) CDW state. Here we report a time-resolved x-ray diffraction study of the growth process of the photoinduced I-CDW domains. The layered nature of the material results in a marked anisotropy in the size of the photoinduced domains of the I-phase. These are found to grow self-similarly, their shape remaining unchanged throughout the growth process. The photoinduced dynamics of the newly formed I-CDW phase was probed at various stages of the growth process using a double pump scheme, where a first pump creates I-CDW domains and a second pump excites the newly formed I-CDW state. We observe larger magnitudes of the coherently excited I-CDW amplitude mode in smaller domains, which suggests that the incommensurate lattice distortion is less stable for smaller domain sizes.