Regensburg 2019 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 27: Two-dimensional Materials III (joint session HL/CPP)

HL 27.3: Vortrag

Mittwoch, 3. April 2019, 10:00–10:15, H36

High magnetic field measurements of interlayer excitons in van der Waals heterostructures — •Johannes Holler1, Michael Kempf1, Jonas Zipfel1, Mariana Ballottin2, Anatolie Mitioglu2, Philipp Nagler1, Fabian Mooshammer1, Alexey Chernikov1, Peter Christianen2, Christian Schüller1, and Tobias Korn31Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Germany — 2High Field Magnet Laboratory (HFML EMFL), Radboud University Nijmegen, Netherlands — 3Institut für Physik, Universität Rostock, Germany

In the recent years, research in the field of two-dimensional materials has intensified a lot. Besides graphene, the most prominent representatives for this field are the transition metal dichalchogenides. These materials exhibit interesting physics in the monolayer, such as spin-valley locking, and by combining them to heterostructures new excitonic properties emerge.

Here, we study MoSe2-WSe2 heterostructures, which create a type-II band alignment. This results in a spatial separation of the electron-hole pairs, leading to the formation of interlayer excitons (IEXs). In low-temperature photoluminescence measurements in magnetic fields up to 30T, we observe a giant valley-selective splitting and a resulting near-unity valley polarization. Furthermore, we probe the valley dynamics of the IEX in dependence of the magnetic field, detecting very long lifetimes in contrast to intralayer excitons. We are able to observe the build-up of the valley polarization after unpolarized excitation, revealing different dynamics and lifetimes for the different valleys.

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