Amy Liu co-authors study of correlations and orbital texture in monolayer 1T-TaSe2

Amy Liu and Oliver Albertini (GSAS `17) are co-authors on a paper, published in Nature Physics,  that reports an experimental study of the electronic properties of the layered material 1T-TaSe2 as it is thinned to a monolayer. The project was led by Michael Crommie at UC Berkeley and involved researchers from multiple institutions. The Georgetown researchers assisted with the theoretical interpretation of the results. 

1T-TaS2 and 1T-TaSe2 are transition-metal dichalcogenides (TMDs) that exhibit unusual insulating states in low-temperature charge-density-wave phases in the bulk (TaS2) and at the bulk surface (TaSe2). The nature of these insulating states — in particular, whether they are driven by strong electron correlations or by interlayer stacking effects — has been widely debated in the literature. Systematic studies of monolayer and few-layer 1T-TMDs offer a way to assess the role of intralayer correlations and interlayer coupling.

Through a combination of scanning tunneling spectroscopy and angle-resolved photoemission investigations of monolayer and few-layer 1T-TaSe2, the authors present evidence that electron correlations drive the insulating behavior of the charge-density-wave phase. These correlations also create an exotic orbital texture in the monolayer. As such, this material promises to be an interesting platform for exploring strong-correlation physics in two dimensions.

[1] Y. Chen et al, Nature Physics (2020) DOI: 10.1038/s41567-019-0744-9

[2] K. J. Franke, F. von Oppen, Nat. Phys. (2020). (News and Views) DOI: 10.1038/s41567-019-0760-9