Intertwined chiral charge orders and topological stabilization of the light-induced state of a prototypical transition metal dichalcogenide

TL;DR

This study reveals a novel, long-range, topologically non-trivial charge order in a transition metal dichalcogenide after a single optical pulse, highlighting intricate chiral domain structures and dislocations that enhance stability, with implications for ultrafast memory devices.

Contribution

First direct observation of a complex, topologically non-trivial charge order in 1T-TaS₂ after a single ultrafast excitation using scanning tunneling microscopy.

Findings

Discovered intricate, long-range charge order with chiral domain tiling.

Identified unpaired dislocations crucial for state stability.

Demonstrated emergence of order after a single optical pulse.

Abstract

The fundamental idea that the constituents of interacting many body systems in complex quantum materials may self-organise into long range order under highly non-equilibrium conditions leads to the notion that entirely new and unexpected functionalities might be artificially created. However, demonstrating new emergent order in highly non-equilibrium transitions has proven surprisingly difficult. In spite of huge recent advances in experimental ultrafast time-resolved techniques, methods that average over successive transition outcomes have so far proved incapable of elucidating the emerging spatial structure. Here, using scanning tunneling microscopy, we report for the first time the charge order emerging after a single transition outcome in a prototypical two-dimensional dichalcogenide 1T-TaS$_2$ initiated by a single optical pulse. By mapping the vector field of charge displacements of the emergent state, we find surprisingly intricate, long-range, topologically non-trivial charge order in which chiral domain tiling is intertwined with unique unpaired dislocations which play a crucial role in enhancing the emergent states remarkable stability. The discovery of the principles that lead to metastability in charge-ordered systems open the way to designing novel emergent functionalities, particularly ultrafast all-electronic non-volatile cryo-memories.