Public Thesis Defense of Alexandre CLOOTS - IMCN

TOWARDS SECOND-PRINCIPLES SIMULATION OF SURFACE PLASMON POLARITONS by Alexandre Cloots

Le vendredi 28 mars 2025 à 15h30 – Auditoire BARB92, place Sainte-Barbe à 1348 Louvain-la-Neuve

This thesis explores new simulation methods to describe surface-plasmon polaritons (SPPs). These are electromagnetic waves that propagate along metal-dielectric interfaces, with important applications in sensing, energy, and nanotechnology. Although the behavior of SPPs in single metal slabs is well understood, the coupling between plasmon modes in multilayer systems has received less attention. In this thesis, we explore the response functions of SPPs in single-slab, double-slab, and two-different-slab systems using the jellium model. Thanks to a comparison with classical models, our study reveals how quantum effects influence the resonance frequencies of these modes. It also details the spatial description of the different SPP modes and unveils how their coupling occurs in two-different-slab systems. These findings provide new insights into the behavior of SPPs, especially in complex nanostructures. Subsequently, the jellium model is used to explore new second-principles (2ndP) schemes aiming at predicting the SPP excitations of large slabs. The simulation at a quantum level of a system of this size is a challenge as first-principles (1stP) computation scales badly with the number of atoms. The 2ndP methods try to circumvent this issue while still accounting for the quantum effects. The idea of the present implementation is to combine the 1stP surface and bulk responses of small systems to extrapolate the SPP dispersion of large slabs. The first dispersion curve of the SPP mode of an 8.4 nm wide jellium equivalent of a Na slab is presented using this method, showing promising results.

Jury members:
Prof. Xavier GONZE (UCLouvain), supervisor
Prof. Luc HENRARD (UNamur), co-supervisor
Prof. Xavier URBAIN (UCLouvain), chairperson
Prof. Gian-Marco RIGNANESE (UCLouvain), secretary
Prof. Vincent LIEGEOIS (UNamur)
Prof. Philippe GHOSEZ (ULiège)

Pay attention: the public defense of Alexandre Cloots will also take place in the form of a videoconference.