Emergent Metastable Order Through Topological Excitation

by Tommy on 27/04/2017

Besides having a Synchrotron Radiation Center in my back yard, and a world class research university in my front yard, Dragan Mihailovic was probably my biggest influence when I first became seriously interested in the spectroscopy of high temperature superconductivity.


Long range electronic order in a metastable state created by ultrafast topological transformation, Yaroslav A. Gerasimenko, Igor Vaskivskyi and Dragan Mihailovic (26 April 2017)

The fundamental idea that many body systems in complex materials may self-organise into long range order under highly non-equilibrium conditions leads to the notion that entirely new emergent states with new and unexpected functionalities might be created. In this paper we show for the first time that a complex metastable state with long range order can be created through a non-equilibrium topological transformation in a transition metal dichalcogenide. Combining ultrafast optical pulse excitation with orbitally-resolved large-area scanning tunnelling microscopy we find subtle, but unambiguous evidence for long range electronic order which is different from all other known states in the system, and whose complex domain structure is not random, but is described by harmonics of the underlying charge density wave order. We show that the structure of the state is topologically distinct from the ground state, elucidating the origins of its remarkable metastability. These fundamental insights on the mechanism open the way to in-situ engineering of the emergent properties of metastable materials with ultrafast laser pulses.

What a long and winding road it’s been.

Pumping and probing.


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