Séminaire CETHIL - Nanoscale radiative heat transfer: theory, applications and open questions

The control of heat transport at nanoscale is today a challenging problem for the development of many technologies. In this presentation I will discuss our last developments in this field by focusing on the control of radiative heat exchanges in near-field regime in various plasmonic structures and I will address some fundamental and controverted problems. The first part of my talk will be devoted to the study of heat transport regimes in many body systems. I will try to answer the question: “how heat spreads in a collection of objects which interact only by radiation?” I will show the existence of superdiffusive [1,2] heat transport regime in diluted systems and of ballistic regimes in dense systems [3]. Next, I will discuss how these systems can be used to control heat exchanges in a similar way as in electronic circuits [4]. To do so I will introduce the building blocks, thermal analogs of diodes [5,6] and of transistor [7] to control, in a similar way as their electronic counterparts, the flow of heat carried by photons, instead of electric current carried by electrons. The third part of my presentation will be devoted to the control of heat exchanges with an external field. In particular I will introduce new thermomagnetic effects [8-11] recently highlighted in many body systems which could open the way to an ultrafast control of radiative exchanges at nanoscale using magneto-optical systems submitted to magnetic fields. To finish I will briefly discuss a fundamental problem which is still in debate: the transition from radiation to conduction regimes between two solids when their separation distance is reduced to subnanometric gaps. I will investigate it in the particular case of metals in interaction by considering all possible channels (electrons, phonons and photons) for heat transfer.