arXiv subjects

Svend-Age Biehs

Publications and source records attributed to Svend-Age Biehs.

At least 55 records · Page 3Linked to original sources

arXiv2017

Radiative heat transfer and nonequilibrium Casimir-Lifshitz force in many-body systems with planar geometry

A general theory of photon-mediated energy and momentum transfer in N-body planar systems out of thermal equilibrium is introduced. It is based on the combination of the scattering theory and the fluctuational-electrodynamics approach in many-body systems. By making a Landauer-like formulation of the heat transfer problem, explicit formulas for the energy transmission coefficients between two distinct slabs as well as the self-coupling coefficients are derived and expressed in terms of the reflection and transmission coefficients of the single bodies. We also show how to calculate local equilibrium temperatures in such systems. An analogous formulation is introduced to quantify momentum transfer coefficients describing Casimir-Lifshitz forces out of thermal equilibrium. Forces at thermal equilibrium are readily obtained as a particular case. As an illustration of this general theoretical framework, we show on three-body systems how the presence of a fourth slab can impact equilibrium temperatures in heat-transfer problems and equilibrium positions resulting from the forces acting on the system.

cond-mat.mes-hall↗

arXiv2017

Thermotronics: toward nanocircuits to manage radiative heat flux

The control of electric currents in solids is at the origin of the modern electronics revolution which has driven our daily life since the second half of 20th century. Surprisingly, to date, there is no thermal analog for a control of heat flux. Here, we summarize the very last developments carried out in this direction to control heat exchanges by radiation both in near and far-field in complex architecture networks.

cond-mat.mes-hall↗

arXiv2017

Near-field heat transfer between multilayer hyperbolic metamaterials

We review the near-field radiative heat flux between hyperbolic materials focusing on multilayer hyperbolic meta-materials. We discuss the formation of the hyperbolic bands, the impact of ordering of the multilayer slabs, as well as the impact of the first single layer on the heat transfer. Furthermore, we compare the contribution of surface modes to that of hyperbolic modes. Finally, we also compare the exact results with predictions from effective medium theory.

cond-mat.mes-hall↗

arXiv2016

Imaging non-local electron transport via local excess noise

Noise is usually a hindrance to signal detection. As stressed by Landauer, however, noise can be an invaluable signal that reveals kinetics of charge particles. Understanding local non-equilibrium electron kinetics at nano-scale is of decisive importance for the development of miniaturized electronic devices, optical nano-devices, and heat management devices. In non-equilibrium conditions electrons cause current fluctuation (excess noise) that contains fingerprint-like information about the electron kinetics. A crucial challenge is hence a local detection of excess noise and its real-space mapping. However, the challenge has not been tackled in existing noise measurements because the noise studied was the spatially integrated one. Here we report the experiment in which the excess noise at ultra-high-frequency(21.3THz), generated on GaAs/AlGaAs quantum well (QW) devices with a nano-scale constriction, is locally detected and mapped for the first time. We use a sharp tungsten tip as a movable, contact-free and noninvasive probe of the local noise, and achieved nano-scale spatial resolution (~50nm). Local profile of electron heating and hot-electron kinetics at nano-scales are thereby visualized for the first time, disclosing remarkable non-local nature of the transport, stemming from the velocity overshoot and the intervalley hot electron transfer. While we demonstrate the usefulness of our experimental method by applying to mesoscopic conductors, we emphasize that the method is applicable to a variety of different materials beyond the conductor, and term our instrument a scanning noise microscope (SNoiM):In general non-equilibrium current fluctuations are generated in any materials including dielectrics, metals and molecular systems. The fluctuations, in turn, excite fluctuating electric and magnetic evanescent fields on the material surface, which can be detected and imaged by our SNoiM.

cond-mat.mes-hall↗

arXiv2016

True thermal antenna with hyperbolic metamaterials

A thermal antenna is an electromagnetic source which emits in its surrounding, a spatially coherent field in the infrared frequency range. Usually, its emission pattern changes with the wavelength so that the heat flux it radiates is weakly directive. Here, we show that a class of hyperbolic materials, possesses a Brewster angle which is weakly dependent on the wavelength, so that they can radiate like a true thermal antenna with a highly directional heat flux. The realization of these sources could open a new avenue in the field of thermal management in far-field regime.

physics.optics↗

arXiv2016

Towards boolean operations with thermal photons

The Boolean algebra is the natural theoretical framework for a classical information treatment. The basic logical operations are usually performed using logic gates. In this Letter we demonstrate that NOT, OR and AND gates can be realized exploiting the near-field radiative interaction in N-body systems with phase change materials. With the recent development of a photon thermal transistor and thermal memory, this result paves the way for a full information treatment and smart solutions for active thermal management at nanoscale with photons.

physics.optics↗

arXiv2016

Hyperbolic waveguide for long-distance transport of near-field heat flux

Heat flux exchanged between two hot bodies at subwavelength separation distances can exceed the limit predicted by the blackbody theory. However this super-Planckian transfer is restricted to these separation distances. Here we demonstrate the possible existence of a super-Planckian transfer at arbitrary large separation distances if the interacting bodies are connected in near-field with weakly dissipating hyperbolic waveguides. This result opens the way to long distance transport of near-field thermal energy.

cond-mat.mes-hall↗

arXiv2016

On Super-Planckian thermal emission in far field regime

We study, in the framework of the Landauer theory, the thermal emission in far-field regime, of arbitrary indefinite planar media and finite size systems. We prove that the flux radiated by the former is bounded by the blackbody emission while, for the second, there is in principle, no upper limit demonstrating so the possibility for a super-Planckian thermal emission with finite size systems.

physics.optics↗

arXiv2015

Giant near-field mediated heat flux at the nanometer scale

In this Letter, we report on quantitative measurements of the absolute near-field mediated heat flux between a gold coated near-field scanning thermal microscope (NSThM) tip and a planar gold sample at nanometer distances of 0.2 nm- 7 nm. We find an extraordinary large heat flux which is more than five orders of magnitude larger than black-body radiation and four orders of magnitude larger than the values predicted by conventional theory of fluctuational electrodynamics. Additionally, we compare our data with different theories of phonon tunneling which might explain a drastically increased heat flux, but are found not to be able to reproduce the distance dependence observed in our experiment. The findings demand modified or even new models of heat transfer across vacuum gaps at nanometer distances.

cond-mat.mes-hall↗

arXiv2015

Heat engine driven by photon tunneling in many-body systems

Near-field heat engines are devices that convert the evanescent thermal field supported by a primary source into usable mechanical energy. By analyzing the thermodynamic performance of three-body near-field heat engines, we demonstrate that the power they supply can be substantially larger than that of two-body systems, showing their strong potential for energy harvesting. Theoretical limits for energy and entropy fluxes in three-body systems are discussed and compared with their corresponding two-body counterparts. Such considerations confirm that the thermodynamic availability in energy-conversion processes driven by three-body photon tunneling can exceed the thermodynamic availability in two-body systems.

cond-mat.mes-hall↗

arXiv2015

Heat flux splitter for near-field thermal radiation

We demonstrate the possibility to efficiently split the near-field heat flux exchanged between graphene nano-disks by tuning their doping. This result paves the way for the developement of an active control of propagation directions for heat fluxes exchanged in near-field throughout integrated nanostructures networks.

physics.optics↗

arXiv2015

Radiative heat flux predictions in hyperbolic metamaterials

The transport of heat mediated by thermal photons in hyperbolic multilayer metamaterials is studied using the fluctuational electrodynamics theory. We demonstrate that in comparison to bulk materials the flux inside layered hyperbolic materials can be transported at much longer distances, making these media very promising for thermal management and for near-field energy harvesting.

cond-mat.mes-hall↗

arXiv2015

Anisotropy enhancement of the Casimir-Polder force between a nanoparticle and graphene

We derive the analytical expressions for the thermal Casimir-Polder energy and force between a spheroidal nanoparticle above a semi-infinite material and a graphene covered interface. We analyze in detail the Casimir-Polder force between a gold nanoparticle and a single sheet of pristine graphene focusing on the impact of anisotropy. We show that the effect of anisotropy, i.e. the shape and orientation of the spheroidal nanoparticle, has a much larger influence on the force than the tunability of graphene. The effect of tuning and anisotropy both add up such that we observe a force which is between 20-50% of that in the ideal metal case which is much larger than the results found for the Casimir force between a metal halfspace and a layer of graphene.

quant-ph↗

arXiv2015

Contactless heat flux control with photonic devices

The ability to control electric currents in solids using diodes and transistors is undoubtedly at the origin of the main developments in modern electronics which have revolutionized the daily life in the second half of 20th century. Surprisingly, until the year 2000 no thermal counterpart for such a control had been proposed. Since then, based on pioneering works on the control of phononic heat currents new devices were proposed which allow for the control of heat fluxes carried by photons rather than phonons or electrons. The goal of the present paper is to summarize the main advances achieved recently in the field of thermal energy control with photons.

physics.optics↗

arXiv2015

Hyperbolic blackbody

The blackbody theory is revisited in the case of thermal electromagnetic fields inside uniaxial anisotropic media in thermal equilibrium with a heat bath. When these media are hyperbolic, we show that the spectral energy density of these fields radically differs from that predicted by Planck's blackbody theory. We demonstrate that the maximum of their spectral energy density is shifted towards frequencies smaller than Wien's frequency making these media apparently colder. Finally, we derive Stefan-Boltzmann's law for hyperbolic media which becomes a quadratic function of the heat bath temperature.

physics.optics↗

arXiv2014

Radiative bistability and thermal memory

We predict the existence of a thermal bistability in many-body systems out of thermal equilibrium which exchange heat by thermal radiation using insulator-metal transition (IMT) materials. We propose a writing-reading procedure and demonstrate the possibility to exploit the thermal bistability to make a volatile thermal memory. We show that this thermal memory can be used to store heat and thermal information (via an encoding temperature) for arbitrary long times. The radiative thermal bistability could find broad applications in the domains of thermal management, information processing and energy storage.

cond-mat.mtrl-sci↗

arXiv2014

Large penetration depth of near-field heat flux in hyperbolic media

We compare super-Planckian thermal radiation between phonon-polaritonic media and hyperbolic metamaterials. In particular, we determine the penetration depth of thermal photons inside the absorbing medium for three different structures: two semi-infinite phonon-polaritonic media supporting surface modes, two multilayer hyperbolic metamaterials and two nanowire hyperbolic metamaterials. We show that for hyperbolic modes the penetration depth can be orders of magnitude larger than for surface modes suggesting that hyperbolic materials are much more preferable for near-field thermophotovoltaic applications than pure phonon-polaritonic materials.

cond-mat.mes-hall↗

arXiv2013

Large enhancement of Forster resonance energy transfer on graphene platforms

In the view of the applications of Forster resonant energy transfer (FRET) in biological systems which especially require FRET in the inrared region we investigate the great advantage of graphene plasmonics in such studies. Focusing on the fundamental aspects of FRET between a donor-acceptor pair on a graphene platform showing that FRET mediated by the plasmons in graphene is broadband and enhanced by six orders of magnitude. We briefly discuss the impact of phonon-polaritonic substrates.

cond-mat.mes-hall↗