Strong suppression of near-field radiative heat transfer by superconductivity in NbN
The result's identifiers
Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68081731%3A_____%2F19%3A00501517" target="_blank" >RIV/68081731:_____/19:00501517 - isvavai.cz</a>
Result on the web
<a href="http://dx.doi.org/10.1103/PhysRevB.99.024511" target="_blank" >http://dx.doi.org/10.1103/PhysRevB.99.024511</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1103/PhysRevB.99.024511" target="_blank" >10.1103/PhysRevB.99.024511</a>
Alternative languages
Result language
angličtina
Original language name
Strong suppression of near-field radiative heat transfer by superconductivity in NbN
Original language description
Near-field (NF) radiative heat transfer (RHT) over vacuum space between closely spaced bodies can exceed the Planck's far-field (FF) values by orders of magnitude. A strong effect of superconductivity on NF RHT between plane-parallel thin-film surfaces of niobium (Nb) was recently discovered and discussed in a short paper [T. Kralik et al., Phys. Rev. B 95, 060503 (2017)]. We present here an extensive set of experimental results on NF as well as FF RHT for geometrically identical samples made of niobium nitride (NbN), including a detailed discussion of the experimental setup and errors. The results with NbN show more precise agreement with theory than the original experiments with Nb. We observed a steep decrease of the heat flux at the transition to superconductivity when the colder sample (absorber) passed from the normal to the superconducting (SC) state (T-c approximate to 15.2 K), corresponding to an up to eightfold contrast between the normal and SC states. This differs dramatically from the situation in the FF regime, where only a weak effect of superconductivity was observed. Surprisingly, the contrast remains sizable even at high temperatures of the hot sample (radiator) with the characteristic energy of radiation far above the SC energy gap. We explain the maximum of contrast in heat flux between the normal and SC states, found at a distance about ten times shorter than the crossover distance between NF and FF heat flux, being d approximate to 1000/ T [mu m]. We analyze in detail the roles of transversal electric (TE) and magnetic (TM) modes in the steep decrease of heat flux below the SC critical temperature and the subsequent flux saturation at low temperatures. Interestingly, we expose experimentally the effect of destructive interference of FF thermal radiation in the vacuum gap, which was observable at temperatures below the absorber superconducting transition.
Czech name
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Czech description
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Classification
Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
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OECD FORD branch
20303 - Thermodynamics
Result continuities
Project
Result was created during the realization of more than one project. More information in the Projects tab.
Continuities
P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)
Others
Publication year
2019
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Physical Review B
ISSN
2469-9950
e-ISSN
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Volume of the periodical
99
Issue of the periodical within the volume
2
Country of publishing house
US - UNITED STATES
Number of pages
12
Pages from-to
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UT code for WoS article
000456301900010
EID of the result in the Scopus database
2-s2.0-85060394582