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Author Gershenzon, E. M.; Gershenzon, M. E.; Goltsman, G. N.; Lulkin, A.; Semenov, A. D.; Sergeev, A. V.
Title Electron-phonon interaction in ultrathin Nb films Type Journal Article
Year 1990 Publication Sov. Phys. JETP Abbreviated Journal Sov. Phys. JETP
Volume (up) 70 Issue 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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Call Number Serial 241
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Author Gershenzon, E. M.; Gol'tsman, G. N.; Potapov, V. D.; Sergeev, A. V.
Title Restriction of microwave enhancement of superconductivity in impure superconductors due to electron-electron interaction Type Journal Article
Year 1990 Publication Solid State Communications Abbreviated Journal Solid State Communications
Volume (up) 75 Issue 8 Pages 639-641
Keywords impure superconductors
Abstract Transition from microwave enhancement of supercurrent to superconductivity suppression is investigated in impure superconductors. It is demonstrated that the frequency range of the enhancement effect narrows with the decrease of the electron mean free path, l, and at l ⩽ 1 nm electron heating is observed in the whole frequency range. Dependences of frequency boundaries on l are explained by taking into account strong electron-electron interaction in impure metals.
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Series Volume Series Issue Edition
ISSN 0038-1098 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1687
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Author Bell, M.; Sergeev, A.; Mitin, V.; Bird, J.; Verevkin, A.; Gol’tsman, G.
Title One-dimensional resistive states in quasi-two-dimensional superconductors: Experiment and theory Type Journal Article
Year 2007 Publication Phys. Rev. B Abbreviated Journal Phys. Rev. B
Volume (up) 76 Issue 9 Pages 094521 (1 to 5)
Keywords uasi-two-dimensional superconductors, NbN
Abstract We investigate competition between one- and two-dimensional topological excitations—phase slips and vortices—in the formation of resistive states in quasi-two-dimensional superconductors in a wide temperature range below the mean-field transition temperature TC0. The widths w=100nm of our ultrathin NbN samples are substantially larger than the Ginzburg-Landau coherence length ξ=4nm, and the fluctuation resistivity above TC0 has a two-dimensional character. However, our data show that the resistivity below TC0 is produced by one-dimensional excitations—thermally activated phase slip strips (PSSs) overlapping the sample cross section. We also determine the scaling phase diagram, which shows that even in wider samples the PSS contribution dominates over vortices in a substantial region of current and/or temperature variations. Measuring the resistivity within 7 orders of magnitude, we find that the quantum phase slips can only be essential below this level.
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ISSN 1098-0121 ISBN Medium
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Notes Approved no
Call Number Serial 1423
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Author Gershenzon, E. M.; Gol'tsman, G. N.; Semenov, A. D.; Sergeev, A. V.
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 (up) 76 Issue 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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ISSN 0038-1098 ISBN Medium
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Notes Approved no
Call Number Serial 1685
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Author Gershenson, M. E.; Gong, D.; Sato, T.; Karasik, B. S.; Sergeev, A. V.
Title Millisecond electron-phonon relaxation in ultrathin disordered metal films at millikelvin temperatures Type Journal Article
Year 2001 Publication Appl. Phys. Lett. Abbreviated Journal
Volume (up) 79 Issue Pages 2049-2051
Keywords HEB detector, FIR, far infrared
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Call Number RPLAB @ s @ heb_eph_interaction_Gershenzon Serial 315
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