Ref HAL: hal-03059594_v1
DOI: 10.1016/j.ijheatmasstransfer.2020.120793
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In dense systems composed of numerous nanoparticles, direct simulations of near-field radiative heat transfer (NFRHT) require considerable computational resources. NFRHT for the simple one-dimensional nanoparticle chains embedded in a non-absorbing host medium is investigated from the point of view of the continuum by means of an approach combining the many-body radiative heat transfer theory and the Fourier law. Effects of the phase change of the insulator-metal transition material (), the complex many-body interaction (MBI) and the host medium relative permittivity on the characteristic effective thermal conductivity (ETC) are analyzed. The ETC for nanoparticle chains below the transition temperature can be as high as 50 times of that above the transition temperature due to the phase change effect. The strong coupling in the insulator-phase nanoparticle chain accounts for its high ETC as compared to the low ETC for the chain at the metallic phase, where there is a mismatch between the characteristic thermal frequency and resonance frequency. The strong MBI is in favor of the ETC. For SiC nanoparticle chains, the MBI even can double the ETC as compared to those without considering the MBI effect. For the dense chains, a strong MBI enhances the ETC due to the strong inter-particles couplings. When the chains go more and more dilute, the MBI can be neglected safely due to negligible couplings. The host medium relative permittivity significantly affects the inter-particles couplings, which accounts for the permittivity-dependent ETC for the nanoparticle chains.

Ref HAL: hal-03044075_v1
DOI: 10.1038/s43246-020-00098-8
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Passive radiative cooling, drawing heat energy of objects to the cold outer space through the atmospheric transparent window, is significant for reducing the energy consumption of buildings. Daytime and nighttime radiative cooling have been extensively investigated in the past. However, radiative cooling which can continuously regulate its cooling temperature, like a valve, according to human need is rarely reported. In this study, we propose a reconfigurable photonic structure, based on the effective medium theory and semi-analytical calculations, for the adaptive radiative cooling by continuous variation of the emission spectra in the atmospheric window. This is realized by the deformation of a one-dimensional polydimethylsiloxane (PDMS) grating and nanoparticle-embedded PDMS thin film when subjected to mechanical stress/strain. The proposed structure reaches different stagnation temperatures under certain strains. A dynamic tuning in emissivity under different strains results in a continuously variable “ON”/“OFF” mode in a particular atmospheric window that corresponds to the deformation-induced fluctuation of the operating temperatures of thereconfigurable nanophotonic structure.

Ref HAL: hal-02973233_v1
Ref Arxiv: 2009.14769
Ref INSPIRE: 1820612
DOI: 10.1103/PhysRevB.102.195422
Ref. & Cit.: NASA ADS
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We derive the Casimir-Polder force and Casimir torque expressions for an anisotropic molecule close to a conducting plane with a tensorial conductivity. We apply our general expressions to the case of a carbon dioxide CO2 molecule close to a plane with pure Hall conductivity and to graphene. We show that the equilibrium position of this linear molecule is with its main axis perpendicular to the surface. We hence conjecture a possible way to exploit the Casimir torque to mechanically improve the performance of CO2 separation membranes useful for an efficient atmospheric CO2 reduction.

Ref HAL: hal-02966760_v1
DOI: 10.1063/5.0022261
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In this work, we have predicted a giant thermal magnetoresistance for the thermal photon transport based on the tunable magnetoplasmon of graphene. By applying an external magnetic field, we find that the heat flux can be modulated by approximately three orders of magnitude. Accordingly, both negative and giant relative thermal magnetoresistance ratios are achieved for magnetic fields with a maximum strength of 4 Tesla. This effect is mainly caused by the suppression and enhancement of scattering interactions mediated by a graphene magnetoplasmon. Specifically, it has never been achieved before for nanoparticles, which have no response to magnetic fields. The effect is remarkable at these reasonable strengths of fields and, thus, has considerable significance for real-life applications. It is also expected to enable technological advances for thermal measurement-based magnetic sensors and magnetically thermal management.The support of this work by the National Natural Science Foundation of China (Nos. 51976044 and 51806047) is gratefully acknowledged. The Heilongjiang Touyan Innovation Team Program is gratefully acknowledged. M.A. acknowledges support from the Institute Universitaire de France, Paris, France (UE).

Ref HAL: hal-02966745_v1
DOI: 10.1364/OL.403044
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In this work, the coupling of magnetoplasmon polaritons (MPP) to surface phonon polaritons (SPhPs) in near-field radiative heat transfer is theoretically investigated. The system is composed of two parallel graphene-coated SiO2 substrates. By applying an external magnetic field, the separated branches of MPPs can couple with SPhPs to form tunable modes. The behavior remolds the energy transport of the system. The relative thermal magnetoresistance ratio can reach values of up to 160% for a magnetic field of 8 T. In addition, the thermal stealthy for the coated graphene is realized by tuning the intensity of fields. This work has substantial importance to graphene-based magneto-optical devices.

Ref HAL: hal-02924253_v1
DOI: 10.1364/OE.402642
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Black phosphorus (BP), as a two-dimensional material, has exhibited unique optoelectronic properties due to its anisotropic plasmons. In the present work, we theoretically propose a radiative thermal switch (RTS) composed of BP gratings in the context of near-field radiative heat transfer. The simply mechanical rotation between the gratings enables considerable modulation of radiative heat flux, especially when combined with the use of non-identical parameters, i.e., filling factors and electron densities of BP. Among all the cases including asymmetric BP gratings, symmetric BP gratings, and BP films, we find that the asymmetric BP gratings possess the most excellent switching performance. The optimized switching factors can be as high as 90% with the vacuum separation d=50 nm and higher than 70% even in the far-field regime d=1 µm. The high-performance switching is basically attributed to the rotatable-tunable anisotropic BP plasmons between the asymmetric gratings. Moreover, due to the twisting principle, the RTS can work at a wide range of temperature, which has great advantage over the phase change materials-based RTS. The proposed switching scheme has great significance for the applications in optoelectronic devices and thermal circuits.

Ref HAL: hal-02923218_v1
DOI: 10.1103/PhysRevResearch.2.033315
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We consider thermal machines powered by locally equilibrium reservoirs that share classical or quantum correlations. The reservoirs are modeled by the so-called collisional model or repeated interactions model. In our framework, two reservoir particles, initially prepared in a thermal state, are correlated through a unitary transformation and afterward interact locally with the two quantum subsystems which form the working fluid. For a particular class of unitaries, we show how the transformation applied to the reservoir particles affects the amount of heat transferred and the work produced. We then compute the distribution of heat and work when the unitary is chosen randomly, proving that the total swap transformation is the optimal one. Finally, we analyze the performance of the machines in terms of classical and quantum correlations established among the microscopic constituents of the machine.