Berlin 2018 – scientific programme

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SYDM: Symposium 2D Materials

SYDM 1: 2D Materials

SYDM 1.3: Invited Talk

Thursday, March 15, 2018, 16:00–16:30, H 0105

Interlayer excitons in layered semiconductor transition metal dichalcogenides — •Steffen Michaelis de Vasconcellos — Physikalisches Institut, WWU Münster, Münster, Germany

Semiconducting transition metal dichalcogenides (TMDCs) such as MoS₂, WSe₂, or MoTe₂ have attracted considerable attention due to their unique physical properties and their usability for novel optoelectronic devices. Unusually strongly bound electron-hole pairs, called excitons, dominate the optical and electronic properties of bulk and monolayer crystals even at room temperature.

In my talk, I will present the discovery of interlayer excitons in bulk TDMC semiconductors. Interlayer excitons, where the electron resides in one layer and the hole in the other, are very promising for achieving Bose-Einstein condensation, superfluidity, and dissipationless current flow. They have been observed in coupled GaAs quantum wells at cryogenic temperatures and artificial TMDC heterostructures. Here, we provide evidence that interlayer excitons also exist in layered bulk crystals. By combining high-field magneto-reflectance experiments and ab initio GW-BSE calculations we identify interlayer excitons in MoTe₂.[1] They form due to strong localization and spin-valley coupling of the charge carriers in the layers. The interlayer excitons are characterized by g-factors with opposite sign and large diamagnetic shift compared with intralayer excitons.

[1] A. Arora et al., Interlayer Excitons in a Bulk van der Waals Semiconductor, Nat. Commun. 8, 639 (2017).