title: Enhancement of near-field radiative heat transfer using polar dielectric thin films.
abstract: Thermal radiative emission from a hot surface to a cold surface plays an important role in many applications, including energy conversion, thermal management, lithography, data storage and thermal microscopy. Recent studies on bulk materials have confirmed long-standing theoretical predictions indicating that when the gap between the surfaces is reduced to tens of nanometres, well below the peak wavelength of the blackbody emission spectrum, the radiative heat flux increases by orders of magnitude. However, despite recent attempts, whether such enhancements can be obtained in nanoscale dielectric films thinner than the penetration depth of thermal radiation, as suggested by theory, remains experimentally unknown. Here, using an experimental platform that comprises a heat-flow calorimeter with a resolution of about 100 pW (ref. 7), we experimentally demonstrate a dramatic increase in near-field radiative heat transfer, comparable to that obtained between bulk materials, even for very thin dielectric films (50-100 nm) when the spatial separation between the hot and cold surfaces is comparable to the film thickness. We explain these results by analysing the spectral characteristics and mode shapes of surface phonon polaritons, which dominate near-field radiative heat transport in polar dielectric thin films.
authors.affiliation: Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Bai
authors.initials: B
authors.lastname: Song
authors.affiliation: Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Yashar
authors.identifier: 0000000315456484
authors.initials: Y
authors.lastname: Ganjeh
authors.affiliation: Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Seid
authors.initials: S
authors.lastname: Sadat
authors.affiliation: Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Dakotah
authors.initials: D
authors.lastname: Thompson
authors.affiliation: Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Anthony
authors.initials: A
authors.lastname: Fiorino
authors.affiliation: Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Madrid 28049, Spain.
authors.forename: Víctor
authors.initials: V
authors.lastname: Fernández-Hurtado
authors.affiliation: Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Madrid 28049, Spain.
authors.forename: Johannes
authors.identifier: 0000000279720646
authors.initials: J
authors.lastname: Feist
authors.affiliation: 1] Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Madrid 28049, Spain [2] Donostia International Physics Center (DIPC), Donostia/San Sebastián 20018, Spain.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Garcia-Vidal
authors.affiliation: Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Madrid 28049, Spain.
authors.forename: Juan Carlos
authors.identifier: 0000000174210682
authors.initials: JC
authors.lastname: Cuevas
authors.affiliation: 1] Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA [2] Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Pramod
authors.initials: P
authors.lastname: Reddy
authors.affiliation: Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Edgar
authors.initials: E
authors.lastname: Meyhofer