Topological Exciton Density Wave in Monolayer <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>WSe</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> </mml:math>
Shan Dong, Yingda Chen, Hongwei Qu, Wenkai Lou, Kai Chang
Abstract
Based on the first-principles calculations coupled with the Bethe-Salpeter equation, the topological exciton density wave is investigated in two-dimensional monolayer WSe_{2}. We find that the topological excitonic insulator phase can exist in monolayer WSe_{2}, and it is robust against in-plane strain. In this system, the energy minimum of exciton bands is shifted to a finite in-plane momentum, forming a Fulde-Ferrell-Larkin-Ovchinnikov-like state. Using the Gross-Pitaevskii equations, stripe-patterned exciton density waves with a nonzero velocity emerge in monolayer WSe_{2}. Our findings pave a new way for exploring the interplay between electron correlation and nontrivial topology.