Optical investigation of the band structure-dependent many-body interactions in monolayer and bilayer transition metal dichalcogenides
ORAL
Abstract
Transition metal dichalcogenide (TMD) heterostructures allow the investigation of many-body interactions between the exciton and a tuneable Fermi-sea, which can be described by the Fermi-polaron model. Experimental and theoretical work has mainly focused on direct bandgap monolayer TMDs, where carriers are doped into the conduction and valence band edges at the ±K valleys. However, there has been recent interest in natural homobilayer TMDs as a host of interlayer excitons and a platform for correlated physics. The band extrema in these systems are often predicted to be located at other high symmetry points (elsewhere to ±K) in the Brillouin zone. Despite this, there is a lack of optical characterisation of the doping-dependent properties in these systems. Here we perform reflection contrast measurements at 4 K on a high-quality dual-gate tuneable device that contains regions of monolayer and bilayer WSe2 and MoSe2. We explain the doping-dependent peak dispersions and magnetic properties of the attractive exciton-polarons that form in the bilayer regions through their distinctive band-structures. We use our observations from the natural bilayers to gain insight into the poorly understood feature that emerges at high carrier concentrations in monolayer WSe2 and other TMD systems, including monolayer MoS2 . Our results further the understanding of monolayer and bilayer TMDs which can help to engineer future optoelectronic devices using these materials.
–
Publication: Optical investigation of the band structure-dependent many-body interactions in monolayer and bilayer transition metal dichalcogenides (manuscript in preparation)
Presenters
-
Aidan J Campbell
- Heriot-Watt Univ
- Heriot-Watt University