| Records |
| Author |
Beck, M.; Klammer, M.; Lang, S.; Leiderer, P.; Kabanov, V. V.; Gol’tsman, G. N.; Demsar, J. |
Title  |
Energy-gap dynamics of superconducting NbN thin films studied by time-resolved terahertz spectroscopy |
Type |
Miscellaneous |
| Year |
2011 |
Publication |
arXiv |
Abbreviated Journal |
|
| Volume |
|
Issue |
|
Pages |
|
| Keywords |
NbN thin film, energy gap dynamics |
| Abstract |
Using time-domain Terahertz spectroscopy we performed direct studies of the photoinduced suppression and recovery of the superconducting gap in a conventional BCS superconductor NbN. Both processes are found to be strongly temperature and excitation density dependent. The analysis of the data with the established phenomenological Rothwarf-Taylor model enabled us to determine the bare quasiparticle recombination rate, the Cooper pair-breaking rate and the electron-phonon coupling constant, \lambda = 1.1 +/- 0.1, which is in excellent agreement with theoretical estimates. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
|
Place of Publication |
|
Editor |
|
| Language |
|
Summary Language |
|
Original Title |
|
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
|
ISBN |
|
Medium |
|
| Area |
|
Expedition |
|
Conference |
|
| Notes |
Duplicated as 641 |
Approved |
no |
| Call Number |
|
Serial |
1388 |
| Permanent link to this record |
| |
|
| |
| Author |
Beck, Matthias; Leiderer, Paul; Kabanov, Viktor V.; Gol'tsman, Gregory; Helm, Manfred; Demsar, Jure |
| Title |
Energy-gap dynamics of a superconductor NbN studied by time-resolved terahertz spectroscopy |
Type |
Abstract |
| Year |
2012 |
Publication |
INIS |
Abbreviated Journal |
INIS |
| Volume |
45 |
Issue |
12 |
Pages |
1-3 |
| Keywords |
NbN energy gap |
| Abstract |
Using time-resolved terahertz (THz) spectroscopy we performed direct studies of the photoinduced suppression and recovery of the SC gap in a conventional SC NbN. Both processes are found to be strongly temperature and excitation density dependent. The analysis of the data with the established phenomenological Rothwarf-Taylor model enabled us to determine the important microscopic constants: the Cooper pair-breaking rate via phonon absorption and the bare quasiparticle recombination rate. From the latter we were able to extract the dimensionless electron-phonon coupling constant, λ=1.1±0.1, in excellent agreement with theoretical estimates. The technique also allowed us to determine the absorbed energy required to suppress SC, which in NbN equals the thermodynamic condensation energy (in cuprates the two differ by an order of magnitude). Finally, we present the first studies of dynamics following resonant excitation with intense narrow band THz pulses tuned to above and below the superconducting gap. These suggest an additional process, particularly pronounced near Tc, that could be attributed to amplification of SC via effective quasiparticle cooling. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
|
Place of Publication |
|
Editor |
|
| Language |
|
Summary Language |
|
Original Title |
|
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
|
ISBN |
|
Medium |
|
| Area |
|
Expedition |
|
Conference |
|
| Notes |
|
Approved |
no |
| Call Number |
|
Serial |
1383 |
| Permanent link to this record |
| |
|
| |
| Author |
Gousev, Y. P.; Semenov, A. D.; Gol'tsman, G. N.; Sergeev, A. V.; Gershenzon, E. M. |
| Title |
Electron-phonon interaction in disordered NbN films |
Type |
Journal Article |
| Year |
1994 |
Publication |
Phys. B Condens. Mat. |
Abbreviated Journal |
Phys. B Condens. Mat. |
| Volume |
194-196 |
Issue |
|
Pages |
1355-1356 |
| Keywords |
NbN films |
| Abstract |
Electron-phonon interaction time has been investigated in disordered films of NbN. A temperatures below 5.5 K tau_eph ~ T -1"6 which is attributed to the renormalisation of phonon spectrum in thin films. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
|
Place of Publication |
|
Editor |
|
| Language |
|
Summary Language |
|
Original Title |
|
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0921-4526 |
ISBN |
|
Medium |
|
| Area |
|
Expedition |
|
Conference |
|
| Notes |
|
Approved |
no |
| Call Number |
|
Serial |
1649 |
| Permanent link to this record |
| |
|
| |
| Author |
Sidorova, M.; Semenov, Alexej D.; Hübers, H.-W.; Ilin, K.; Siegel, M.; Charaev, I.; Moshkova, M.; Kaurova, N.; Goltsman, G. N.; Zhang, X.; Schilling, A. |
| Title |
Electron energy relaxation in disordered superconducting NbN films |
Type |
Journal Article |
| Year |
2020 |
Publication |
Phys. Rev. B |
Abbreviated Journal |
Phys. Rev. B |
| Volume |
102 |
Issue |
5 |
Pages |
054501 (1 to 15) |
| Keywords |
NbN SSPD, SNSPD, HEB, bandwidth, relaxation time |
| Abstract |
We report on the inelastic-scattering rate of electrons on phonons and relaxation of electron energy studied by means of magnetoconductance, and photoresponse, respectively, in a series of strongly disordered superconducting NbN films. The studied films with thicknesses in the range from 3 to 33 nm are characterized by different Ioffe-Regel parameters but an almost constant product qTl (qT is the wave vector of thermal phonons and l is the elastic mean free path of electrons). In the temperature range 14–30 K, the electron-phonon scattering rates obey temperature dependencies close to the power law 1/τe−ph∼Tn with the exponents n≈3.2–3.8. We found that in this temperature range τe−ph and n of studied films vary weakly with the thickness and square resistance. At 10 K electron-phonon scattering times are in the range 11.9–17.5 ps. The data extracted from magnetoconductance measurements were used to describe the experimental photoresponse with the two-temperature model. For thick films, the photoresponse is reasonably well described without fitting parameters, however, for thinner films, the fit requires a smaller heat capacity of phonons. We attribute this finding to the reduced density of phonon states in thin films at low temperatures. We also show that the estimated Debye temperature in the studied NbN films is noticeably smaller than in bulk material. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
|
Place of Publication |
|
Editor |
|
| Language |
|
Summary Language |
|
Original Title |
|
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
2469-9950 |
ISBN |
|
Medium |
|
| Area |
|
Expedition |
|
Conference |
|
| Notes |
|
Approved |
no |
| Call Number |
|
Serial |
1266 |
| Permanent link to this record |
| |
|
| |
| Author |
Lusche, R.; Semenov, A.; Ilin, K.; Siegel, M.; Korneeva, Y.; Trifonov, A.; Korneev, A.; Goltsman, G.; Vodolazov, D.; Hübers, H.-W. |
| Title |
Effect of the wire width on the intrinsic detection efficiency of superconducting-nanowire single-photon detectors |
Type |
Journal Article |
| Year |
2014 |
Publication |
J. Appl. Phys. |
Abbreviated Journal |
J. Appl. Phys. |
| Volume |
116 |
Issue |
4 |
Pages |
043906 (1 to 9) |
| Keywords |
NbN SSPD, SNSPD, TaN |
| Abstract |
A thorough spectral study of the intrinsic single-photon detection efficiency in superconducting TaN and NbN nanowires with different widths has been performed. The experiment shows that the cut-off of the intrinsic detection efficiency at near-infrared wavelengths is most likely controlled by the local suppression of the barrier for vortex nucleation around the absorption site. Beyond the cut-off quasi-particle diffusion in combination with spontaneous, thermally activated vortex crossing explains the detection process. For both materials, the reciprocal cut-off wavelength scales linearly with the wire width where the scaling factor agrees with the hot-spot detection model. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
|
Place of Publication |
|
Editor |
|
| Language |
|
Summary Language |
|
Original Title |
|
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0021-8979 |
ISBN |
|
Medium |
|
| Area |
|
Expedition |
|
Conference |
|
| Notes |
|
Approved |
no |
| Call Number |
|
Serial |
1357 |
| Permanent link to this record |
