Ultrafast Coherent Control of Structural Orders in a Layered Rhenium Disulfide

The optimal functionalities of correlated matter often appear at emergent structural orders involving entangled changes in the electronic states and the underlying nuclear lattices. Here, we study a layered rhenium disulfide (ReS₂), an atypical transition metal dichalcogenide with its unique electron-rich nature of Re atoms. This yields the formation of stable, high-order superlattice variants, which emerge from a distinct six-fold stacking order when subjected to photothermal annealing using light pulses ranging from femto- to nanoseconds. Electronically driven coherent melting and reordering of the superlattices in ReS₂ upon photoexcitation is unfolded with time-resolved electron diffraction in ultrafast electron microscopy, mapping the full phase trajectory of the structural orders therein supported by atomic-resolution imaging. We discuss the identity of the high-order structural arrangement and the origin of its emergence. Our discovery on the structure and electron-correlated behavior between active degrees of freedom in a low-dimensional material system gives a rich palette to control emerging multitude of intriguing phases and complex transitions with electronic manipulations and ultimately to boost an extra flexibility to design new quantum phenomena.