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Author Gershenzon, E. M.; Gershenzon, M. E.; Goltsman, G. N.; Lulkin, A.; Semenov, A. D.; Sergeev, A. V. url  openurl
  Title Electron-phonon interaction in ultrathin Nb films Type Journal Article
  Year 1990 Publication Sov. Phys. JETP Abbreviated Journal Sov. Phys. JETP  
  Volume 70 Issue (up) 3 Pages 505-511  
  Keywords Nb films  
  Abstract A study was made of the heating of electrons in normal resistive states of superconducting thin Nb films. The directly determined relaxation time of the resistance of a sample and the rise of the electron temperature were used to find the electron-phonon interaction time rep,, The dependence of rep, on the mean free path of electrons re,, a 1-'demonstrated, in agreement with the theoretical predictions, that the contribution of the inelastic scattering of electrons by impurities to the energy relaxation process decreased at low temperatures and the observed temperature dependence rep, a T 2 was due to a modification of the phonon spectrum in thin fllms.

1. Much new information on the electron-phonon interaction time?;,, in thin films of normal metals and superconductors has been published recently. This information has been obtained mainly as a result of two types of measurement. One includes experiments on weak electron localization investigated by the method of quantum interference corrections to the conductivity of disordered conductors, which can be used to find the relaxation time T, of the phase of the electron wave function. In the absence of the scattering of electrons by paramagnetic impurities the relaxation time T, is associated with the most effective process of energy relaxation: T;= TL+ rep;, where T,, is the electronelectron relaxation time. At low temperatures, when the dependence T; a T is exhibited by thin disordered films, the dominant channel is that of the electron-electron relaxation and there is a lower limit to the temperature range in which rep, can be investigated.
 
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  Notes Approved no  
  Call Number Serial 241  
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Author Gershenzon, E. M.; Gershenzon, M. E.; Gol'tsman, G. N.; Semyonov, A. D.; Sergeev, A. V. url  doi
openurl 
  Title Heating of electrons in superconductor in the resistive state due to electromagnetic radiation Type Journal Article
  Year 1984 Publication Solid State Communications Abbreviated Journal Solid State Communications  
  Volume 50 Issue (up) 3 Pages 207-212  
  Keywords Nb HEB  
  Abstract The effect of heating electrons with respect to phonons in a thin superconducting film driven into the resistive state by the current and the external magnetic field has been observed and investigated. This effect caused by the electromagnetic radiation is manifested in the increased resistance of the film and is not selective over the frequency range from 1010 to 1015 Hz. That the effect is frequency independent under the conditions of strong electron scattering caused by static defects is explained by the decisive role of electron -electron collisions in forming the distribution function. The characteristic time of resistance change, obtained experimentally, corresponds to the relaxation time of the order parameter near the superconducting transition and to the relaxation time of the nonelastic electron-phonon interaction at lower temperatures and in lower magnetic fields.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0038-1098 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1709  
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Author Gershenzon, E. M.; Gol'tsman, G. N.; Semenov, A. D.; Sergeev, A. V. url  doi
openurl 
  Title Mechanism of picosecond response of granular YBaCuO films to electromagnetic radiation Type Journal Article
  Year 1990 Publication Solid State Communications Abbreviated Journal Solid State Communications  
  Volume 76 Issue (up) 4 Pages 493-497  
  Keywords YBCO HTS detectors  
  Abstract The ultrafast mechanisms of radiation detection in granular YBaCuO films are studied in the wide wavelength range from millimeter to near infrared. With the rise of radiation frequency the Josephson detection at the grain boundary weak links is replaced by electron heating into the grains. This change occurs in the submillimeter wavelength range. Electron-phonon relaxation time τeph is determined by direct measurements and analyses quasistationary electron heating. Temperature dependence of τeph at T ≤ 40 K was found to be τeph ∼ T−1. The results show that detectors with the response time of few picoseconds at nitrogen temperature are attainable.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0038-1098 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1685  
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Author Semenov, A. D.; Goghidze, I. G.; Gol’tsman, G. N.; Sergeev, A. V.; Gershenzon, E. M. url  doi
openurl 
  Title Evidence for the spectral dependence of nonequilibrium picosecond photoresponse of YBaCuO thin films Type Journal Article
  Year 1993 Publication Appl. Phys. Lett. Abbreviated Journal Appl. Phys. Lett.  
  Volume 63 Issue (up) 5 Pages 681-683  
  Keywords YBCO HTS detectors, nonequilibrium  
  Abstract The transient voltage photoresponse of current biased YBaCuO thin films to 20 ps laser pulses of 0.63 and 1.54 μm wavelengths is measured for temperatures around the superconducting transition region. The fast picosecond decay of the response is followed by a slow nanosecond relaxation which is associated with the bolometric effect. The magnitude of the fast component of the response varies in proportion to the square root of wavelength that plausibly reflects multiplication processes of photoexcited electrons via electron–electron scattering and interaction with high energy phonons.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0003-6951 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1655  
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Author Aksaev, E. E.; Gershenzon, E. M.; Gol'tsman, G. N.; Semenov, A. D.; Sergeev, A. V. url  openurl
  Title Interaction of electrons with thermal phonons in YBa2Cu3O7-δ films at low temperatures Type Journal Article
  Year 1989 Publication JETP Lett. Abbreviated Journal JETP Lett.  
  Volume 50 Issue (up) 5 Pages 283-286  
  Keywords YBCO HTS films  
  Abstract The time of electron-phonon interaction tau(eph) in YBaCuO films at low temperatures is studied. This is measured as the time of resistance relaxation in the resistive state of the superconducter, and is also determined from the increase in resistance under the action of radiation. Consistent results of these methods show that resistance relaxation in the resistive state is caused by cooling of the electron subsystem with respect to the phonon subsystem. The time tau(eph) is found to be inversely proportional to the temperature and comes to 80 ps when T = 1.6 K and 5 ps when T = 30 K. 6 refs.  
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  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1690  
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