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Lecture

Joan van der Waals colloquium - online

Date
Friday 27 November 2020
Time
Location
Zoom
Room
Online

Probing interlayer interaction in van der Waals materials

Most layered materials can be exfoliated to atomically thin sheets, the most famous being graphite (yielding graphene). This opens up the possibility to stack different layer types together, so as to build up novel materials in a LEGO-like fashion. A long run aim is to learn how to pre-program the properties of such systems, as a novel kind of ‘designer materials’. 

The extent to which stacked van der Waals systems differ from their parent materials is governed by the interaction between the layers. Remarkably, this interaction can be further tuned by twisting layers with respect to each other. The latter can actually give rise to remarkable properties such as superconductivity, as recently observed in twisted bilayer graphene [1,2].
Here, we investigate interlayer interactions using several new techniques developed in our lab, all rooted in low-energy electron microscopy (LEEM) [3-5]. Basically, we are using slow electrons (kinetic energy: 0-100 eV) to probe van der Waals systems, both microscopically and spectroscopically. Not only does this allow us to locally determine layer stacking and twist angles, we also obtain information on the unoccupied band structure of the (new) system. Additionally, our recent introduction of low-energy transmission electron microscopy (eV-TEM) allows us to probe inelastic interaction effects of electrons with layered materials [5].


[1] Y. Cao et al. Nature 556, 80-84 (2018)
[2] S. Lisi, Tj. Benschop, T. de Jong et al.
Nature Physics (2020)
[3] J. Jobst et al., Nature Communications 6, 8926 (2015)
[4] J. Jobst et al., Nature Communications 7, 13621 (2016)
[5] D. Geelen et al. Phys. Rev. Lett. 123, 086802 (2019)

The opening act is given by Martin Baaske (LION): "Label-Free Plasmonic Detection of Single Protein Molecules on-the-Fly”. 

The Zoom link is:

https://us02web.zoom.us/j/85449906697?pwd=bEMzVVFkMU1yWEdkUEtVMStkQ1dPQT09

Meeting ID: 854 4990 6697

Passcode: 822762

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