• Elu/nommé au comité national CNRS
• Elu/nommé au CS/CSD CNRS ou IRD
• Expert ANR
• Élu au Bureau de l'IUF - Ministère ENESR

• Membre d'un pool d'experts
• Direction/codirection de laboratoire
• Direction d'équipe
• Responsable de formations
• Responsable de diplôme (M2)

• Physique/Physique Quantique
  
• Physique/Matière Condensée/Gaz Quantiques
  
• Physique/Physique/Agrégats Moléculaires et Atomiques
  
• Physique/Physique/Physique Atomique
  
• Physique/Physique/Optique
  

Thermal diodes, which allow heat transfer in a preferential direction while being blocked in a reverse direction, have numerous applications in thermal management, information processing, energy harvesting, etc. Typical materials of thermal diodes in previous works include phase-change and magneto-optical materials. However, such thermal diodes depend highly on specific working temperatures or external magnetic fields. In this work, we propose a near-field radiative thermal diode (NFRTD) based on two Weyl semimetal (WSM) nanoparticles (NPs) mediated by a WSM planar substrate, which works without an external magnetic field and with flexible temperatures. Numerical results show that the maximum rectification ratio of NFRTD can be up to 2673 when the emitter is 200 K and receiver is 180 K, which exceeds the maximum value reported in some previous works by more than 10 times. The underlying physical mechanism is the strong coupling of the localized plasmon modes in the NPs and nonreciprocal surface plasmon polaritons in the substrate. In addition, we calculate the distribution of the Green's function and reflection coefficient to investigate nonreciprocal energy transfer in NFRTDs. Finally, we discuss the effects of momentum separation on the rectification performance of the NFRTD. This work demonstrates the great potential of WSMs in thermal rectification and paves a path for designing high-performance NFRTDs.

We present a numerical approach for the solution of electromagnetic scattering from a dielectric cylinder partially covered with graphene. It is based on a classical Fourier-Bessel expansion of the fields inside and outside the cylinder to which we apply ad hoc boundary conditions in the presence of graphene. Due to the singular nature of the electric field at the edges of the graphene sheet, we introduce auxiliary boundary conditions. The result is a particularly simple and efficient method allowing the study of diffraction from such structures. We also highlight the presence of multiple plasmonic resonances that we ascribe to the surface modes of the coated cylinder.

Over the last few years, broken symmetry within crystals has attracted extensive attention since it can improve the control of light propagation. In particular, low-symmetry Bravais crystal can support shear polaritons, which has great potential in thermal photonics. In this work, we first use the fluctuation-dissipation theorem to investigate mechanisms of near-field thermal radiation (NFTR) in a low-symmetry Bravais crystal. The NFTR between such crystal slabs is nearly four orders of magnitude larger than the blackbody limit, demonstrating its remarkable potential for noncontact heat dissipation for nanoscale circuits or other devices. Moreover, we report a form of twist-induced near-field thermal control system employing the low-symmetry Bravais crystal medium (β-Ga2O3), showing that this crystal can serve as an excellent platform for twist-induced near-field thermal control. Due to the intrinsic shear effect, the twist-induced modulation supported by low-symmetry Bravais crystal exceeds that by high-symmetry crystal. We further clarify how the shear effect affects the twist-induced thermal-radiation modulation supported by hyperbolic and elliptical polaritons and show that the shear effect significantly enhances the twist-induced thermal control induced by the elliptical polariton mode. These results open directions for thermal-radiation control in low-symmetry materials, including geological minerals, common oxides, and organic crystals.

Using the self-consistent Born approximation, we study a topological phase transition appearing in bulk HgCdTe crystals induced uncorrelated disorder due to both randomly distributed impurities and fluctuations in Cd composition. By following the density-of-states evolution, we clearly demonstrate the topological phase transition, which can be understood in terms of the disorder-renormalized mass of Kane fermions. We find that the presence of a heavy-hole band in HgCdTe crystals leads to the topological phase transition at much lower disorder strength than is expected for conventional three-dimensional topological insulators. Our theoretical results can also be applied to other narrow-gap zinc-blende semiconductors such as InAs, InSb, and their ternary alloys InAsSb.

In the first part we will show a study of the Casimir torque between two metallic one-dimensional gratings rotated by an angle θ with respect to each other. We find that, for infinitely extended gratings, the Casimir energy is anomalouslydiscontinuous at θ = 0, due to a critical zero-order geometric transition between a 2D- and a 1D-periodicsystem. We will comment on the relevant implication of this finding.In the second part I will discuss the Radiative heat transfer (RHT) and radiative thermal energy (RTE) for two-dimensional (2D) nanoparticle ensembles in the framework of many-body radiative heat transfer theory. We consider nanoparticles made of different materials: metals (Ag), polar dielectrics (SiC), or insulator-metallic phase-change materials(VO2). We start by investigating the RHT between two parallel 2D finite-size square-lattice nanoparticleensembles, with particular attention to many-body interactions (MBI) effects. We fix the particle radius (a)as the smallest length scale, and we describe the electromagnetic scattering from particles within the dipoleapproximation. Depending on the minimal distance between the in-plane particles (the lattice spacing p forperiodic systems), on the separation d between the two lattice and on the thermal wavelength,we systematically analyze the different physical regimes characterizing the RHT. Four regimes are identified,rarefied regime, dense regime, non-MBI regime, and MBI regime, respectively.