Thesis defense of Marta Reina

Thesis defense of Marta Reina, PhD student in the Nanophotonics group at Laboratoire Charles Fabry, on 12 October 2021 at 10h00am in the Auditorium on the theme : " Conduction-radiation coupling at the nanoscale ".

Abstract :

Two bodies at different temperatures experience a photon-mediated heat exchange, even when separated by vacuum. This radiative heat flux, limited by Stefan-Boltzmann’s law in the far field can exceed this limit even by orders of magnitude for shorter distances, in the near-field regime. Surprisingly, very few efforts have been devoted so far to the study of the coupling of radiative heat transfer and conduction in a solid body. In this thesis we face this problem and study the dynamics of mechanical oscillators, predicting that a phase-transition oscillator driven by near-field heat exchanges has a bistable thermomechanical behavior around its critical temperature, opening the way to a possible Boolean treatment of information from heat flux at microscale. We also develop a theory to describe the conduction-radiation coupling between solids of arbitrary size separated by a subwavelength gap. We show that, as a result of the temperature profile induced by the coupling with conduction, the radiative heat flux exchanged between two parallel slabs at nanometric distances can be orders of magnitude smaller than the one predicted by the conventional theory. As a result of this coupling, we highlight a strong slowing down of relaxation dynamics in the extreme near-field regime.