Strong suppression of near-field radiative heat transfer by superconductivity in NbN

Kód výsledku v 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>

Výsledek na webu

<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>

Jazyk výsledku

angličtina

Název v původním jazyce

Strong suppression of near-field radiative heat transfer by superconductivity in NbN

Popis výsledku v původním jazyce

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.

Název v anglickém jazyce

Strong suppression of near-field radiative heat transfer by superconductivity in NbN

Popis výsledku anglicky

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.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

20303 - Thermodynamics

Projekt

Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2019

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Physical Review B

ISSN

2469-9950

e-ISSN

—

Svazek periodika

99

Číslo periodika v rámci svazku

2

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

12

Strana od-do

—

Kód UT WoS článku

000456301900010

EID výsledku v databázi Scopus

2-s2.0-85060394582