1. Twist-angle engineering of excitonic quantum interference and optical nonlinearities in stacked 2D semiconductors
- Author
-
Paulo E. Faria Junior, Jaroslav Fabian, Sebastian Bange, John M. Lupton, Bartomeu Monserrat, Bo Peng, Martin Gmitra, Jonas M. Bauer, Kai-Qiang Lin, Peng, Bo [0000-0001-6406-663X], Monserrat, Bartomeu [0000-0002-4233-4071], Bange, Sebastian [0000-0002-5850-264X], Lupton, John M [0000-0002-7899-7598], Apollo - University of Cambridge Repository, and Lupton, John M. [0000-0002-7899-7598]
- Subjects
639/766/119/1000/1018 ,Nonlinear optics ,Materials science ,Chalcogenide ,Electromagnetically induced transparency ,Exciton ,Science ,General Physics and Astronomy ,FOS: Physical sciences ,02 engineering and technology ,Electronic structure ,Two-dimensional materials ,01 natural sciences ,Article ,General Biochemistry, Genetics and Molecular Biology ,5108 Quantum Physics ,chemistry.chemical_compound ,Condensed Matter::Materials Science ,0103 physical sciences ,Dispersion (optics) ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,140/125 ,010306 general physics ,639/624/400/385 ,Condensed Matter - Materials Science ,Multidisciplinary ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed matter physics ,business.industry ,Condensed Matter::Other ,Bilayer ,ddc:530 ,Materials Science (cond-mat.mtrl-sci) ,General Chemistry ,021001 nanoscience & nanotechnology ,530 Physik ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,5104 Condensed Matter Physics ,Semiconductor ,chemistry ,0210 nano-technology ,business ,51 Physical Sciences ,Order of magnitude ,Physics - Optics ,Optics (physics.optics) - Abstract
Twist-engineering of the electronic structure in van-der-Waals layered materials relies predominantly on band hybridization between layers. Band-edge states in transition-metal-dichalcogenide semiconductors are localized around the metal atoms at the center of the three-atom layer and are therefore not particularly susceptible to twisting. Here, we report that high-lying excitons in bilayer WSe2 can be tuned over 235 meV by twisting, with a twist-angle susceptibility of 8.1 meV/°, an order of magnitude larger than that of the band-edge A-exciton. This tunability arises because the electronic states associated with upper conduction bands delocalize into the chalcogenide atoms. The effect gives control over excitonic quantum interference, revealed in selective activation and deactivation of electromagnetically induced transparency (EIT) in second-harmonic generation. Such a degree of freedom does not exist in conventional dilute atomic-gas systems, where EIT was originally established, and allows us to shape the frequency dependence, i.e., the dispersion, of the optical nonlinearity., Here, the authors report on the large twist-angle susceptibility of excitons involving upper conduction bands in transition metal dichalcogenide bilayers. These high-lying excitons couple with band-edge excitons, and give rise to nonlinear quantum-optical processes that become tuneable by twisting.
- Published
- 2021