Suchergebnisse

Interview mit Rafael Roncagliolo über die ökonomischen und politischen Hintergründe der Neuen Internationalen Informationsordnung und ihre Bedeutung für das peruanische Pressewesen

We present here a theoretical analysis that demonstrates that the far-field radiative heat transfer between objects with dimensions smaller than the thermal wavelength can overcome the Planckian limit by orders of magnitude. To guide the search for super-Planckian far-field radiative heat transfer, we make use of the theory of fluctuational electrodynamics and derive a relation between the far-field radiative heat transfer and the directional absorption efficiency of the objects involved. Guided by this relation, and making use of state-of-the-art numerical simulations, we show that the far-field radiative heat transfer between highly anisotropic objects can largely overcome the black-body limit when some of their dimensions are smaller than the thermal wavelength. In particular, we illustrate this phenomenon in the case of suspended pads made of polar dielectrics like SiN or SiO2. These structures are widely used to measure the thermal transport through nanowires and low-dimensional systems and can be employed to test our predictions. Our work illustrates the dramatic failure of the classical theory to predict the far-field radiative heat transfer between micro- and nanodevices ; We acknowledge funding from the Spanish MINECO (FIS2015-64951-R, MAT2014-53432- C5-5-R, FIS2014-53488-P, FIS2017-84057-P), the Comunidad de Madrid (S2013/MIT-2740), the European Union Seventh Framework Programme (FP7-PEOPLE-2013-CIG- 630996, FP7-PEOPLE-2013-CIG-618229), and the European Research Council (ERC-2011-AdG-290981 and ERC-2016- STG-714870). V.F.-H. acknowledges support from "la Caixa" Foundation and J.C.C. thanks the DFG and SFB767 for sponsoring his stay at the University of Konstanz as Mercator Fellow

This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Photonics, copyright © 2018 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acsphotonics.8b00328 ; Very recently it has been predicted that the far-field radiative heat transfer between two macroscopic systems can largely overcome the limit set by Planck's law if one of their dimensions becomes much smaller than the thermal wavelength (λTh≈ 10 μm at room temperature). To explore the ultimate limit of the far-field violation of Planck's law, here we present a theoretical study of the radiative heat transfer between two-dimensional (2D) materials. We show that the far-field thermal radiation exchanged by two coplanar systems with a one-atom-thick geometrical cross section can be more than 7 orders of magnitude larger than the theoretical limit set by Planck's law for blackbodies and can be comparable to the heat transfer of two parallel sheets at the same distance. In particular, we illustrate this phenomenon with different materials such as graphene, where the radiation can also be tuned by a external gate, and single-layer black phosphorus. In both cases the far-field radiative heat transfer is dominated by TE-polarized guiding modes, and surface plasmons play no role. Our predictions provide a new insight into the thermal radiation exchange mechanisms between 2D materials ; This work has been financially supported by the Spanish MINECO (FIS2015-64951-R, MAT2014-53432-C5-5-R, and FIS2017-84057-P), the Comunidad de Madrid (S2013/MIT-2740), the European Union Seventh Framework Programme (FP7-PEOPLE-2013-CIG-630996), and the European Research Council (ERC-2011-AdG-290981 and ERC-2016-STG-714870). V.F.-H. acknowledges support from "la Caixa" Foundation. V.F.-H. and J.C.C. (Mercator Fellow) thank the DFG and SFB767 for sponsoring their stay at the University of Konstanz.