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Gershenzon EM, Gol'tsman GN, Potapov VD, Sergeev AV. Restriction of microwave enhancement of superconductivity in impure superconductors due to electron-electron interaction. Phys B Condens Mat. 1991;169(1-4):629–30.
Abstract: Transition from microwave enhancement of supercurrent to superconductivity suppression is investigated in impure superconductors. It is demonstrated that frequency range of enhancement effect narrows with the decrease of electron mean free path, ℓ, and at ℓ⩽1nm 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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Aksaev EE, Gershenzon EM, Gol'tsman GN, Mirskij GI, Semenov AD. Submillimetric spectrometer-relaxometer based on backward-wave tubes with picosecond time resolution. Pribory i Tekhnika Eksperimenta. 1991;34(2):125–31.
Abstract: The high-sensitive automatic spectrometer-relaxometer based on backward-wave tubes in the range of 4÷0.25 mm was described permitting to study the response kinetics of sample under investigation in any point of this range with the resolution time of 10-11 s. The relaxation measurements were conducted using oscillation beats of two adequate tubes, the frequency of one of them was fixed, while that of the other one was changeable. The amplitude-frequency characteristic of the response under the conditions of synchronous reception was recorded at beat frequency variation from 107 to 1010 Hz. The high sensitivity was reached by decreasing the device recording band down to 100 Hz in the whole measuring range.
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Gershenzon EM, Gol'tsman GN, Semenov AD, Sergeev AV. Mechanism of picosecond response of granular YBaCuO films to electromagnetic radiation. Solid State Communications. 1990;76(4):493–7.
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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Varyukhin SV, Zakharov AA, Gershenzon EM, Gol'tsman GN, Ptitsyna NG, Chulkova GM. AC losses and submillimeter absorption in single crystals La2CuO4. Phys B Condens Mat. 1990;165-166:1269–70.
Abstract: The La2CuO4 single crystals were used to carry out the measurements of transmission spectra within the submillimeter range of wavelengths, as well as the capacitance C and conductivity G in the region of acoustic frequencies of the metal-dielectric-La2Cu04 system at low temperatures. The optical spectra display a threshold character. There takes place a sharp decreasing of transmission signal in the energy range of hυ>1.5meV. The C(ω,T) and G(ω,T) dependences have a universal form characteristic of relaxation processes of the Debye type. The relaxation time dependence displays a thermoactivation character τ(T)-exp(ξ/T) with a gap value of ξ≃2meV,coinciding with the optical one. It is assumed that there exist excitations with a characteristic energy ~ 2meV in La2Cu04.A possible nature of the revealed low-energy excitations is discussed.
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Gershenzon EM, Gol'tsman GN, Potapov VD, Sergeev AV. Restriction of microwave enhancement of superconductivity in impure superconductors due to electron-electron interaction. Solid State Communications. 1990;75(8):639–41.
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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