title: All-optical materials design of chiral edge modes in transition-metal dichalcogenides.
abstract: Monolayer transition-metal dichalcogenides are novel materials which at low energies constitute a condensed-matter realization of massive relativistic fermions in two dimensions. Here, we show that this picture breaks for optical pumping-instead, the added complexity of a realistic materials description leads to a new mechanism to optically induce topologically protected chiral edge modes, facilitating optically switchable conduction channels that are insensitive to disorder. In contrast to graphene and previously discussed toy models, the underlying mechanism relies on the intrinsic three-band nature of transition-metal dichalcogenide monolayers near the band edges. Photo-induced band inversions scale linearly in applied pump field and exhibit transitions from one to two chiral edge modes on sweeping from red to blue detuning. We develop an ab initio strategy to understand non-equilibrium Floquet-Bloch bands and topological transitions, and illustrate for WS2that control of chiral edge modes can be dictated solely from symmetry principles and is not qualitatively sensitive to microscopic materials details.
authors.affiliation: Department of Applied Physics, Stanford University, Stanford, California 94305, USA.|Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University, Stanford, California 94025, USA.
authors.forename: Martin
authors.initials: M
authors.lastname: Claassen
authors.affiliation: Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University, Stanford, California 94025, USA.
authors.forename: Chunjing
authors.initials: C
authors.lastname: Jia
authors.affiliation: Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University, Stanford, California 94025, USA.|Department of Physics and Astrophysics, University of North Dakota, Grand Forks, North Dakota 58202, USA.
authors.forename: Brian
authors.identifier: 0000-0002-3747-8484
authors.initials: B
authors.lastname: Moritz
authors.affiliation: Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University, Stanford, California 94025, USA.|Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA.
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Devereaux