Ballistic near-field heat transport in dense many-body systems

Abstract

Radiative heat-transport mediated by near-field interactions is known to be superdiffusive in dilute, many-body systems. In this Letter we use a generalized Landauer theory of radiative heat transfer in many-body planar systems to demonstrate a nonmonotonic transition from superdiffusive to ballistic transport in dense systems. We show that such a transition is associated to a change of the polarization of dominant modes, leading to dramatically different thermal relaxation dynamics spanning over three orders of magnitude. This result could have important consequences on thermal management at nanoscale of many-body systems.The theory of near-field radiative heat transfer has for many decades remained largely limited to two-body systems [1][2][3][4][5][6]. Recently, heat transport in many-body systems has also been considered in the context of nanoparticles [7][8][9][10] and multilayer geometries, such as photonic crystals [11,12] and hyperbolic metamaterials [13][14][15]. The focus of much of this work has been the study of systems in which the steady-state temperature distribution of a set of internal bodies is a priori known and dictated via contact with large heat reservoirs. There are, however, situations in which a full study of heat transport necessitates an account of thermal relaxation through radiative channels. A first step in this direction has been made by generalizing Rytov's theory of fluctutational electrodynamics to describe radiative transfer in many-body geometries with varying temperature distributions, including nanoparticle systems [17][18][19], multilayer configurations [16,[20][21][22][23][24][25][26][27][28], and more generally, arbitrary geometries that include the possibility of inhomogeneously varying temperature profiles [29,30]. Furthermore, heat transport within a collection of nanoparticles has been studied in Ref. [31], and the existence of a superdiffusive regime has been found, albeit within a dipolar approximation.In the present Letter, we employ a recently developed, exact theoretical framework [32] to investigate near-field radiative heat transport in N -body systems consisting of parallel planar slabs separated by vacuum, in which radiation is the only source of thermal relaxation. We show that the temperature dynamics and steady-state profile of the system depend strongly on geometric parameters such as the system density, which imply different heat-transport regimes. In particular, we prove the existence of a nonmonotonic transition between a superdiffusive regime, previously observed in Ref. [31], and a ballistic regime that appears in denser media and that also leads to dramatically faster relaxation dynamics. We also show that this transition is associated with a change in the polarization of the dominant modes in the

Limitations of kinetic theory to describe near-field heat exchanges in many-body systems

“…Following these theoretical developments numerous many-body effects have been highlighted in these systems. For example, anomalous heat transports regimes have been demonstrated 21,22 , N -body amplification mechanisms 23 or magneto-optical effects 24 , paving the way to new functionalities for thermal management at nanoscale [25][26][27] . In this work we question the limits of the kinetic approach to describe the radiative heat exchange in Nbody systems.…”

Radiative heat transfer and radiative thermal energy for two-dimensional nanoparticle ensembles

“…By investigating NFRHT in the dense particle system from the point of view of continuum medium, the heat superdiffusion was found in the plasmonic nanostructure networks due to NFRHT based on the fractional diffusion theory [30]. Then, a similar heat superdiffusion was found in the periodically arranged planar SiC plates [41]. Recently, a new method was developed to calculate the diffusive radiative thermal conductivity of arbitrary collections of nanoparticles [42], which is an important progress relative to the kinetic method used to calculate the effective radiative thermal conductivity of 1D nanoparticle chain [43][44][45].…”

The Progress and Future of Near-field Radiative Heat Transfer

“…By cooperation with conventional and specific materials, such as uniaxial hyperbolic materials, magneto-optical materials, Weyl semimetals, phase change materials, etc., the many-body system can exhibit the waveguide effect, photon thermal hall effect, superdiffusive and ballistic heat transport, nonreciprocity, anomalous photon thermal hall effect, etc. [22,[38][39][40][41][42] Meanwhile, the many-body system can greatly enrich the potential application of NFRHT, including the thermal transistor, heat engine, thermal logic gates, nonreciprocal thermal diode, heat flux switch, heat pump, etc. [22,25,27,[42][43][44][45] Therefore, compared with the two-body system, the many-body system may exhibit more anomalous NFRHT phenomena and potential applications.…”