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Théorie du rayonnement matière et phénomènes quantiques
(24) Production(s) de l'année 2024


Spontaneous breaking of timereversal symmetry and timecrystal states in chiral atomic systems
Auteur(s): Antezza M.
(Séminaires)
Queen's University of Belfast (Belfast, GB), 20241029
Résumé: We present a theoretical study of the interaction between an atom characterized by a degenerate ground state and a reciprocal environment, such as a semiconductor nanoparticle, without the presence of external bias. Our analysis reveals that the combined influence of the electron's intrinsic spin magnetic moment on the environment and the chiral atomic dipolar transitions may lead to either the spontaneous breaking of timereversal symmetry or the emergence of timecrystallike states with remarkably long relaxation times. The different behavior is ruled by the handedness of the precession motion of the atom's spin vector, which is induced by virtual chiraldipolar transitions. Specifically, when the relative orientation of the precession angular velocity and the electron spin vector is as in a spinning top, the system manifests timecrystallike states. Conversely, with the opposite relative orientation, the system experiences spontaneous symmetry breaking of time reversal symmetry. Our findings introduce a mechanism for the spontaneous breaking of timereversal symmetry in atomic systems, and unveil an exciting opportunity to engineer a nonreciprocal response at the nanoscale, exclusively driven by the quantum vacuum fluctuations.



Unconventional Thermophotonic Charge Density Wave
Auteur(s): Zhou Chenglong, Torbatian Zahra, Yang Shuihua, Zhang Yong, Yi Hingliang, Antezza M., Novko Dino, Qiu Chengwei
(Article) Publié:
Physical Review Letters, vol. 133 p.066902 (2024)
DOI: 10.1103/PhysRevLett.133.066902
Résumé: Chargeorder states of broken symmetry, such as charge density wave (CDW), are able to induce exceptional physical properties, however, the precise understanding of the underlying physics is still elusive. Here, we combine fluctuational electrodynamics and density functional theory to reveal an unconventional thermophotonic effect in CDWbearing TiSe2, referred to as thermophotonicCDW (????????CDW). The interplay of plasmon polariton and CDW electron excitations give rise to an anomalous negative temperature dependency in thermal photons transport, offering an intuitive fingerprint for a transformation of the electron order. Additionally, the demonstrated nontrivial features of ????????CDW transition hold promise for a controllable manipulation of heat flow, which could be extensively utilized in various fields such as thermal science and electron dynamics, as well as in nextgeneration energy devices.



Nearfield radiative heat transfer between a nanoparticle and a graphene grating
Auteur(s): Luo M., Jeyar Y., Guizal B., Antezza M.
(Article) Publié:
Physical Review B, vol. 110 p.075423 (2024)
DOI: 10.1103/PhysRevB.110.075423
Résumé: We investigate the nearfield radiative heat transfer between a normally and/or laterally shifted nanoparticle and a planar fused silica slab coated with a strip graphene grating. For this study, we develop and use a scattering matrix approach derived from Fourier modal method augmented with local basis functions. We find that adding a graphene sheet coating on the slab can already enhance the heat flux by about 85%. We show that by patterning the graphene sheet coating into a grating, the heat flux is further increased, and this happens thanks to the a topological transition of the plasmonic modes from circular to hyperbolic one, which allows for more energy transfer. The lateral shift affects the accessible range of high???? modes and thus affects the heat flux, too. By moving the nanoparticle laterally above the graphene grating, we can obtain an optimal heat flux with strong chemical potential dependence above the strips. For a fixed graphene grating period (????=1µm) and not too large normal shift (separation ????<800nm), two different types of lateral shift effects (e.g., enhancement and inhibition) on heat transfer have been observed. As the separation ???? is further increased, the lateral shift effect becomes less important. We show that the lateral shift effect is sensitive to the geometric factor ????/????. Two distinct asymptotic regimes are proposed: (1) the inhibition regime (????/????<0.85), where the lateral shift reduces the heat transfer and (2) the neutral regime (????/????≥0.85) where the effect of the lateral shift is negligible. In general, we can say that the geometric factor ????/????≈0.85 is a critical point for the lateral shift effect. Our predictions can have relevant implications to the radiative heat transfer and energy management at the nano/microscale.



Nearfield radiative heat transfer between graphenecovered Weyl semimetals
Auteur(s): Hu Yang, Wu Xiaohu, Huang Xiuquam, Liu Haotuo, Antezza M.
(Article) Publié:
Materials Today Communications, vol. 40 p.110192 (2024)
DOI: 10.1016/j.mtcomm.2024.110192
Résumé: Polariton manipulations introduce novel approaches to modulate the nearfield radiative heat transfer (NFRHT). Our theoretical investigation in this study centers on NFRHT in graphenecovered Weyl semimetals (WSMs). Our findings indicate variable heat flux enhancement or attenuation, contingent on chemical potential of graphene. Enhancement or attenuation mechanisms stem from the coupling or decoupling of surface plasmon polaritons (SPPs) in the graphene/WSM heterostructure. The graphenecovered WSM photon tunneling probabilities variation is demonstrated in detail. This research enhances our comprehension of SPPs within the graphene/ WSM heterostructure and suggests methods for actively controlling NFRHT.



NEARFIELD RADIATIVE HEAT TRANSFER BETWEEN GRAPHENEBASED NANOSTRUCTURES:
LATERALLY SHIFTED GRATINGS AND NANOPARTICLEGRATING CONFIGURATIONS
Auteur(s): Antezza M.
Conférence invité: 32nd International Materials Research Congress Sociedad Mexicana de Materiales (cancun, MX, 20240818)
Résumé: We examine the nearfield radiative heat transfer between graphenebased nanostructures including parallel and laterally shifted graphene gratings and between nanoparticles and graphene gratings. We use the scattering matrix formalism together with a Local Basis Function Fourierbased method to calculate the graphene grating electromagnetic scattering. We study how the lateral shift can effectively modulate the heat transfer for different filling factor and chemical potential, and the role played by different electromagnetic modes in these structures on the radiative energy transfer. This studies has the potential to unveil new avenues for harnessing the lateral shift effect on radiative heat transfer in graphenebased nanodevices.



CasimirLifshitz force for graphenecovered gratings
Auteur(s): Jeyar Y., Luo M., Guizal B., Chan Ho bun, Antezza M.
(Article) Publié:
Physical Review B, vol. 110 p.045446 (2024)
DOI: 10.1103/PhysRevB.110.045446
Résumé: We study the CasimirLifshitz force (CLF) between a gold plate and a graphenecovered dielectric grating. Using a scattering matrix (Smatrix) approach derived from the Fourier modal method (FMM), we find a significant enhancement in the CLF as compared to a mere dielectric slab coated with graphene, over a wide range of temperatures. Additionally, we demonstrate that the CLF depends strongly on the chemical potential of graphene, with maximal effects observed at lower filling fractions. Finally, we analyze the Casimir force gradient between a gold sphere and a graphenecoated dielectric grating, highlighting potential avenues for experimental measurements.



Favorable and unfavorable manybody interactions for nearfield radiative heat transfer in nanoparticle networks
Auteur(s): Luo M., Zhao Junming, Liu Linhua, Antezza M.
(Article) Publié:
Journal Of Quantitative Spectroscopy And Radiative Transfer, vol. 327 p.109129 (2024)
DOI: 10.1016/j.jqsrt.2024.109129
Résumé: Nearfield radiative heat transfer (NFRHT) in pointdipole nanoparticle networks is complicated due to the multiple scattering of thermally excited electromagnetic wave (namely, manybody interaction, MBI). The MBI regime is analyzed using the manybody radiative heat transfer theory at the particle scale for networks of a few nanoparticles. Effect of MBI on radiative heat diffusion in networks of a large number of nanoparticles is analyzed using the normaldiffusion radiative heat transfer theory at the continuum scale. An influencing factor is defined to numerically figure out the border of the different manybody interaction regimes. The whole space near the two nanoparticles can be divided into four zones, nonMBI zone, enhancement zone, inhibition zone and forbidden zone, respectively. Enhancement zone is relatively smaller than the inhibition zone, so many particles can lie in the inhibiting zone that the inhibition effect of manybody interaction on NFRHT in nanoparticle networks is common in literature. Analysis on the radiative thermal energy confirms that multiple scattering caused by the inserted scatterer accounts for the enhancement and inhibition of NFRHT. By arranging the nanoparticle network in aspect of structures and optical properties, the MBI can be used to modulate radiative heat diffusion characterized by the radiative effective thermal conductivity over a wide range, from inhibition (over 55% reduction) to amplification (30 times of magnitude). To achieve a notable MBI, it is necessary to introduce particles that have resonances wellmatched with those of the particles of interest, irrespective of their match with the Planckian window. This work may help for the understanding of the thermal radiation in nanoparticle networks.
