17 research outputs found
Intertwined chiral charge orders and topological stabilization of the light-induced state of a prototypical transition metal dichalcogenide
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 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.Comment: preprint version of the paper published in npj Quantum Material
Quantum billiards with correlated electrons confined in triangular transition metal dichalcogenide monolayer nanostructures created by laser quench
Forcing systems though fast non-equilibrium phase transitions offers the
opportunity to study new states of quantum matter that self-assemble in their
wake. Here we study the quantum interference effects of correlated electrons
confined in monolayer quantum nanostructures, created by femtosecond
laser-induced quench through a first-order polytype structural transition in a
layered transition-metal dichalcogenide material. Scanning tunnelling
microscopy of the electrons confined within equilateral triangles, whose
dimensions are a few crystal unit cells on the side, reveals that the
trajectories are strongly modified from free-electron states both by electronic
correlations and confinement. Comparison of experiments with theoretical
predictions of strongly correlated electron behaviour reveals that the
confining geometry destabilizes the Wigner/Mott crystal ground state, resulting
in mixed itinerant and correlation-localized states intertwined on a length
scale of 1 nm. Occasionally, itinerant-electron states appear to follow quantum
interferences which are suggestive of classical trajectories (quantum scars).
The work opens the path toward understanding the quantum transport of electrons
confined in atomic-scale monolayer structures based on
correlated-electron-materials