Ref HAL: hal-04128464_v1
Ref Arxiv: 2305.18946
Ref INSPIRE: 2663857
DOI: 10.1103/PhysRevB.108.115412
Ref. & Cit.: NASA ADS
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Résumé:

We study the non equilibrium Casimir-Lifshitz force between graphene-based parallel structures held at different temperatures and in presence of an external thermal bath at a third temperature. The graphene conductivity, which is itself a function of temperature, as well as of chemical potential, allows us to tune in situ the Casimir-Lifshitz force. We explore different non equilibrium configurations while considering different values of the graphene chemical potential. Particularly interesting cases are investigated, where the force can change sign going from attractive to repulsive or where the force becomes non monotonic with respect to chemical potential variations, contrary to the behaviour under thermal equilibrium.

Résumé:

I will discuss recent results: (i) on the Casimir torque between two metallic one-dimensional gratings rotated by an angle θ with respect to each other [1]; and (ii) on the quantitative effect of the presence of the metallic contact grid at the front side of thermophotovoltaic cells, based on a rigorous approach [2]. This effect can be tremendous both in terms of optical and electrical (resistive) losses. However, it has been theoretically either discarded or studied by means of extremely simplified models (like shadowing methods, consisting in just ignoring the fraction of the cell surface covered by metal). ------- [1] Mauro Antezza, H. B. Chan, Brahim Guizal, V.N. Marachevsky, Riccardo Messina, Mingkang Wang, Phys. Rev. Lett. 124 013903 (2020). [2] K. Austry, Y. Jeyar, M. Luo, B. Guizal, R. Messina, R. Vaillon, and M. Antezza, in preparation (2023)

Résumé:

(1) We will discuss recent results: (i) on the Casimir torque between two metallic one-dimensional gratings rotated by an angle θ with respect to each other [1]; and (ii) on the Casimir force occurring between interpenetrating gratings [2]. These findings pave the way to the design of a contactless quantum vacuum torsional spring, and sensors with possible relevance to micro and nanomechanical devices. (2) We propose a scheme for a quantum thermal machine made by atoms interacting with a single nonequilibrium electromagnetic field. We show that these machines can deliver all thermodynamic tasks (cooling, heating, and population inversion) by establishing quantum coherence with the body on which they act. Remarkably, this system allows these machines to reach efficiencies at maximum power very close to the Carnot limit, which is much more than in existing models [3]. ------- [1] Mauro Antezza, H. B. Chan, Brahim Guizal, V.N. Marachevsky, Riccardo Messina, Mingkang Wang, Phys. Rev. Lett. 124 013903 (2020) [2] Mingkang Wang, L. Tang, C.Y. Ng, Riccardo Messina, Brahim Guizal, J. A. Crosse, Mauro Antezza, C.T. Chan, H.B. Chan, Nature Communication 12 600 (2021) [3] Bruno Leggio, Bruno Bellomo, and Mauro Antezza, Phys. Rev. A 91, 012117 (2015)

DOI: 10.1103/PhysRevMaterials.7.035201
Résumé:

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.

DOI: 10.1103/PhysRevE.107.025306
Résumé:

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.

Ref HAL: hal-03806711_v1
Ref Arxiv: 2206.03022
DOI: 10.1103/PhysRevB.106.155404
Ref. & Cit.: NASA ADS
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Résumé:

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.

Ref HAL: hal-03783120_v1
Ref Arxiv: 2206.14561
DOI: 10.1103/PhysRevB.106.115203
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé:

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.

Commentaires: 8 pages, 4 figures