PhD defense – Maxime Ardisson

On Wednesday, March 8, at 2:00 p.m. (TRT Auditorium), Maxime Ardisson will defend his PhD thesis titled “Control of Magnon-Photon Coupling in Hybrid RF Architectures”, supervised by Vincent Castel, Romain Lebrun, and Isabella Boventer.

Summary : 

Cavity magnonics has attracted considerable attention for the past decade. The ability to couple cavity photons with collective spin excitations in magnetic materials — known as spin waves — holds great promise for both quantum information processing and memory, as well as classical radiofrequency (RF) systems for information and communication technologies (ICT).

The hybridization between the quanta of spin waves, called magnons, and cavity photons occurs when their frequencies coincide. This condition can be achieved by tuning the magnon resonance frequency via an externally applied DC magnetic field. The result from this hybridization gives rise to a quasiparticle known as cavity-magnon-polariton (CMP).

The work presented in this doctoral thesis focuses on controlling such hybridization through tailored cavity architectures and by optimizing the positioning of the magnetic samples within those cavities. Firstly, a three-port reentrant cavity was modeled using finite-element simulations to analyze magnon-photon interaction. The study aimed to achieve comprehensive characterization of the hybrid system and control over the coupling regime.

A toroidal substrate-integrated waveguide supporting degenerate circularly polarized modes was used to achieve chiral magnon-photon coupling. In this study, strategic positioning of multiple magnetic samples enabled hybridization selectivity between eigenmodes and controllable non-reciprocity. Simulations and theoretical analysis highlighted the coupling phase as a key quantity governing the non-reciprocal behavior of the system. A defect-based photonic crystal cavity was modeled and experimentally validated as a platform for coherent magnon-photon coupling. The influence of sample size on transmission amplitude and coupling strength was studied for different geometries and frequency scales. This work contributes to cavity magnonics by introducing novel resonator architectures and providing simulation guidelines for magnon-photon hybridization modeling.