arXiv subjects

Riccardo Messina

Publications and source records attributed to Riccardo Messina.

At least 37 records · Page 2Linked to original sources

arXiv2022

Coupling between conduction and near-field radiative heat transfer in tip-plane geometry

We analyze the coupling between conduction and radiative heat transfer in near-field regime between two coaxial cylinders separated by a vacuum gap. By solving the heat transport equation in the steady-state regime between metals or polar materials we highlight a flux saturation mechanism for the radiative transfer even without non-local effect. In the case of polar materials this saturation occurs in the separation distances range of 1 to 10 nm which can be experimentally explored.

cond-mat.mes-hall↗

arXiv2022

Graphene-based enhancement of near-field radiative-heat-transfer rectification

We present a thermal device based on the near-field interaction between two substrates made of a polar and a metal-insulator-transition material. As a result of the temperature dependence of the optical properties, this device acts as a thermal rectifier, implying a strong asymmetry in the heat flux when reversing the two temperatures. By covering both substrates with a graphene sheet we show a significant enhancement of rectification coefficient. By investigating the flux spectral properties along with its distance dependence, we prove that this enhancement is associated to a change in the power-law dependence of heat flux with respect to the separation distance in the electrostatic regime due to the presence of graphene sheets. Our results highlight the promising role of graphene-based hybrid structures in the domain of nanoscale thermal management.

physics.app-ph↗

arXiv2021

Strong slowing down of the thermalization process of solids interacting in extreme near-field regime

When two solids at different temperatures are separated by a vacuum gap they relax toward their equilibrium state by exchanging heat either by radiation, phonon or electron tunneling, depending on their separation distance and on the nature of materials. The interplay between this exchange of energy and its spreading through each solid entirely drives the relaxation dynamics. Here we highlight a significant slowing down of this process in the extreme near-field regime at distances where the heat flux exchanged between the two solids is comparable or even dominates over the flux carried by conduction inside each solid. This mechanism, leading to a strong effective increase of the system thermal inertia, should play an important role in the temporal evolution of thermal state of interacting solids systems at nanometric and subnanometric scales.

cond-mat.mes-hall↗

arXiv2021

Radiative cooling induced by time-symmetry breaking in periodically-driven systems

We theoretically study the thermal relaxation of many-body systems under the action of oscillating external fields. When the magnitude or the orientation of a field is modulated around values where the pairwise heat-exchange conductances depend non-linearly on this field, we demonstrate that the time symmetry is broken during the evolution of temperatures over a modulation cycle. We predict that this asymmetry enables a pumping of heat which can be used to cool down faster the system. This effect is illustrated through different magneto-optical systems under the action of an oscillating magnetic field.

cond-mat.mes-hall↗

arXiv2021

Strong geometry dependence of the Casimir force between interpenetrated rectangular gratings

Quantum fluctuations give rise to Casimir forces between two parallel conducting plates, the magnitude of which increases monotonically as the separation decreases. By introducing nanoscale gratings to the surfaces, recent advances have opened opportunities for controlling the Casimir force in complex geometries. Here, we measure the Casimir force between two rectangular gratings in regimes not accessible before. Using an on-chip detection platform, we achieve accurate alignment between the two gratings so that they interpenetrate as the separation is reduced. Just before interpenetration occurs, the measured Casimir force is found to have a geometry dependence that is much stronger than previous experiments, with deviations from the proximity force approximation reaching a factor of ~500. After the gratings interpenetrate each other, the Casimir force becomes non-zero and independent of displacement. This work shows that the presence of gratings can strongly modify the Casimir force to control the interaction between nanomechanical components.

quant-ph↗

arXiv2020

Conduction-radiation coupling between two closely-separated solids

In the theory of radiative heat exchanges between two closely-spaced bodies introduced by Polder and van Hove, no interplay between the heat carriers inside the materials and the photons crossing the separation gap is assumed. Here we release this constraint by developing a general theory to describe the conduction-radiation coupling between two solids of arbitrary size separated by a subwavelength separation gap. We show that, as a result of the temperature profile induced by the coupling with conduction, the radiative heat flux exchanged between two parallel slabs at nanometric distances can be several orders of magnitude smaller than the one predicted by the conventional theory. These results could have important implications in the fields of nanoscale thermal management, near-field solid-state cooling and nanoscale energy conversion.

cond-mat.mes-hall↗

arXiv2020

Near-field Radiative Heat Transfer in Many-Body Systems

Many-body physics aims to understand emergent properties of systems made of many interacting objects. This article reviews recent progress on the topic of radiative heat transfer in many-body systems consisting of thermal emitters interacting in the near-field regime. Near-field radiative heat transfer is a rapidly emerging field of research in which the cooperative behavior of emitters gives rise to peculiar effects which can be exploited to control heat flow at the nanoscale. Using an extension of the standard Polder and van Hove stochastic formalism to deal with thermally generated fields in $N$-body systems, along with their mutual interactions through multiple scattering, a generalized Landauer-like theory is derived to describe heat exchange mediated by thermal photons in arbitrary reciprocal and non-reciprocal multi-terminal systems. In this review, we use this formalism to address both transport and dynamics in these systems from a unified perspective. Our discussion covers: (i) the description of non-additivity of heat flux and its related effects, including fundamental limits as well as the role of nanostructuring and material choice, (ii) the study of equilibrium states and multistable states, (iii) the relaxation dynamics (thermalization) toward local and global equilibria, (iv) the analysis of heat transport regimes in ordered and disordered systems comprised of a large number of objects, density and range of interactions, and (v) the description of thermomagnetic effects in magneto-optical systems and heat transport mechanisms in non-Hermitian many-body systems. We conclude this review by listing outstanding challenges and promising future research directions.

cond-mat.mes-hall↗

arXiv2020

Mechanical relations between conductive and radiative heat transfer

We present a general nonequilibrium Green's function formalism for modeling heat transfer in systems characterized by linear response that establishes the formal algebraic relationships between phonon and radiative conduction, and reveals how upper bounds for the former can also be applied to the latter. We also propose an extension of this formalism to treat systems susceptible to the interplay of conductive and radiative heat transfer, which becomes relevant in atomic systems and at nanometric and smaller separations where theoretical descriptions which treat each phenomenon separately may be insufficient. We illustrate the need for such coupled descriptions by providing predictions for a low-dimensional system of carbyne wires in which the total heat transfer can differ from the sum of its radiative and conductive contributions. Our framework has ramifications for understanding heat transfer between large bodies that may approach direct contact with each other or that may be coupled by atomic, molecular, or interfacial film junctions.

cond-mat.mes-hall↗

arXiv2020

Scalable radiative thermal logic gates based on nanoparticle networks

We discuss the design of the thermal analog of logic gates in systems made of a collection of nanoparticles. We demonstrate the possibility to perform NOT, OR, NOR, AND and NAND logical operations at submicrometric scale by controlling the near-field radiative heat exchanges between their components. We also address the important point of the role played by the inherent non-additivity of radiative heat transfer in the combination of logic gates. These results pave the way to the development of compact thermal circuits for information processing and thermal management, which might also be realized with quantum dots.

physics.app-ph↗

arXiv2020

Many-body radiative heat pumping

We introduce a local radiative heat-pumping effect between two bodies in a many-body system, obtained by periodically modulating both the temperature and the position of an intermediate object using an external source of energy. We show that the magnitude and the sign of energy flow can be tuned by changing the oscillation amplitude and dephasing of the two parameters. This many-body effect paves the way for an efficient and active control of heat fluxes at the nanoscale.

cond-mat.mes-hall↗

arXiv2019

Saturation of radiative heat transfer due to many-body thermalization

Radiative heat transfer between two bodies saturates at very short separation distances due to the nonlocal optical response of the materials. In this work, we show that the presence of radiative interactions with a third body or external bath can also induce a saturation of the heat transfer, even at separation distances for which the optical response of the materials is purely local. We demonstrate that this saturation mechanism is a direct consequence of a thermalization process resulting from many-body interactions in the system. This effect could have an important impact in the field of nanoscale thermal management of complex systems and in the interpretation of measured signals in thermal metrology at the nanoscale.

cond-mat.mes-hall↗

arXiv2019

Thermomechanical bistability of phase-transition oscillators driven by near-field heat exchange

Systems with multistable equilibrium states are of tremendous importance in information science to conceive logic gates. Here we predict that simple phase-transition oscillators driven by near-field heat exchanges have a bistable thermomechanical behavior around their critical temperature, opening so the way to a possible boolean treatment of information from heat flux at microscale.

cond-mat.mes-hall↗

arXiv2019

Giant Casimir torque between rotated gratings and the $θ=0$ anomaly

We study 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 anomalously discontinuous at $θ=0$, due to a critical zero-order geometric transition between a 2D- and a 1D-periodic system. This transition is a peculiarity of the grating geometry and does not exist for intrinsically anisotropic materials. As a remarkable practical consequence, for finite-size gratings, the torque per area can reach extremely large values, increasing without bounds with the size of the system. We show that for finite gratings with only 10 period repetitions, the maximum torque is already 60 times larger than the one predicted in the case of infinite gratings. These findings pave the way to the design of a contactless quantum vacuum torsional spring, with possible relevance to micro- and nano-mechanical devices.

cond-mat.mes-hall↗

arXiv2019

Radiative thermal diode driven by non-reciprocal surface waves

We demonstrate the possibility to rectify the nanoscale radiative heat flux between two nanoparticles by coupling them with the nonreciprocal surface modes of a magneto-optical substrate in a Voigt configuration. When the non-reciprocal medium supports a surface wave in the spectral window where heat exchanges take place the rectification coefficient can reach large values opening so the way to the design of true thermal diodes.

cond-mat.mes-hall↗

arXiv2018

Magneto-thermoplasmonics: from theory to applications

We review recent theoretical developments on the nanoscale radiative heat transfer in magneto-optical many-particle systems. We discuss in detail the circular heat flux, the giant magneto-resistance effect, the persistent heat current, and the thermal Hall effect for light in such systems within the framework of fluctuational electrodynamics, using the dipolar approximation. We show that the directionality of heat flux in such systems can in principle be understood by analyzing the competing contributions to the heat exchange of the magnetic-field-dependent dipolar resonances of quantum numbers m = +1 and m = -1. Some potential applications of these effects to thermal and magnetic sensing are also briefly discussed.

cond-mat.mes-hall↗

arXiv2018

Heat transfer between two metals through subnanometric vacuum gaps

We theoretically investigate the heat transfer between two metals across a vacuum gap in extreme near-field regime by quantifying the relative contribution of electrons, phonons and photons. We show that electrons play a dominant role in the heat transfer between two metals at subnanometric distance subject to a temperature gradient. Moreover, we demonstrate that this effect is dramatically amplified in the presence of an applied bias voltage. These results could pave the way to novel strategies for thermal management and energy conversion in extreme near-field regime.

cond-mat.mes-hall↗

arXiv2018

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

We investigate the radiative heat transfer along a chain of nanoparticles using both a purely kinetic approach based on the solution of a Boltzmann transport equation and an exact method (Landauer's approach) based on fluctuational electrodynamics. We show that the kinetic theory generally fails to predict properly the heat flux transported along the chain both at close (near-field regime) and large separation (far-field regime) distances. We report a deviation of a factor two between the heat fluxes predicted by the two approaches in the diffusive regime of heat transport and we show that this difference becomes even greater than two orders of magnitude in the ballistic regime.

cond-mat.mes-hall↗

arXiv2018

Near-field refrigeration and tunable heat exchange through four-wave mixing

We modify and extend a recently proposed four-wave mixing scheme [Opt. Express 25 (19),23164 (2017)] for achieving near-field thermal upconversion and energy transfer, to demonstrate efficient thermal refrigeration at low intensities $\sim 10^{-9}$W/m$^2$ over a wide range of gap sizes (from tens to hundreds of nanometers) and operational temperatures (from tens to hundreds of Kelvins). We further exploit the scheme to achieve magnitude and directional tunability of near-field heat exchange between bodies held at different temperatures.

cond-mat.mes-hall↗