Ultrafast nano-imaging of the order parameter in a structural phase transition

TL;DR

This paper introduces ultrafast dark-field electron microscopy to visualize and analyze the dynamics of charge-density wave domains during a structural phase transition in 1T-TaS2, revealing relaxation pathways and domain wall behavior.

Contribution

The study presents a novel ultrafast dark-field electron microscopy technique for real-time imaging of order parameter dynamics in materials undergoing phase transitions.

Findings

Visualization of charge-density wave domain evolution

Identification of relaxation pathways post laser excitation

Insights into domain wall dynamics during phase transition

Abstract

Understanding microscopic processes in materials and devices that can be switched by light requires experimental access to dynamics on nanometer length and femtosecond time scales. Here, we introduce ultrafast dark-field electron microscopy, tailored to map the order parameter across a structural phase transition. We track the evolution of charge-density wave domains in 1T-TaS2 after ultrashort laser excitation, elucidating relaxation pathways and domain wall dynamics. The unique benefits of selective contrast enhancement will inspire future beam shaping technology in ultrafast transmission electron microscopy.