PhD Candidate
GEORGIOS VAILAKIS
gvailakis@materials.uoc.gr
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Title
Theoretical study of two-dimensional nanostructures
Supervisor
KOPIDAKIS GEORGIOS, Associate Professor, Materials Science & Technology Dept. - UOC
Committee Members
REMEDIAKIS IOANNIS, Associate Professor, Materials Science & Technology Dept. - UOC
PAPAZOGLOU DIMITRIOS, Associate Professor, Materials Science & Technology Dept. - UOC
Abstract
Layer by layer stacking of two-dimensional materials gives rise to “van der Waals” (vdW) heterostructures of nanometer thickness and clean interfaces. These systems often exhibit extraordinary properties and present novel challenges for theory. Superconductivity of twisted bilayer graphene at the magic angle, interlayer excitons in transition metal dichalcogenide (TMD) heterostructures, and optoelectronic properties of TMD/graphene heterostructures, are examples, among others, where vdW heterostructures significantly differ from their monolayer constituents. Theoretical models can answer emerging fundamental questions and identify possible candidates with properties tailored for specific applications from all the range of unique vdW heterostructures. We will perform density functional theory (DFT) calculations for the atomic and electronic structure of vdW heterostructures consisting of combinations of TMD monolayers and graphene. Due to the large size of the supercells, DFT calculations are very demanding and need careful interpretation using non-trivial computational tools, which we need to develop. Additionally, we will perform post-DFT calculations for more accurate results on intralayer and interlayer excitons, and other key optoelectronic properties. Our DFT-based results, combined with data from experiments, will be used in a multiscale approach to investigate interesting phenomena observed in vdW heterostructures at length scales orders of magnitude larger than interatomic distances. This will require significant effort in developing semi-empirical and empirical models. Besides explaining observed phenomena, we expect that our predictions will be useful in new experiments and applications.