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Gershenzon, E. M., Gol'tsman, G. N., Potapov, V. D., & Sergeev, A. V. (1991). Restriction of microwave enhancement of superconductivity in impure superconductors due to electron-electron interaction. Phys. B Condens. Mat., 169(1-4), 629–630.
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, E. E., Gershenzon, E. M., Gol'tsman, G. N., Mirskij, G. I., & Semenov, A. D. (1991). Submillimetric spectrometer-relaxometer based on backward-wave tubes with picosecond time resolution. Pribory i Tekhnika Eksperimenta, 34(2), 125–131.
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, E. M., Gol'tsman, G. N., Semenov, A. D., & Sergeev, A. V. (1990). Mechanism of picosecond response of granular YBaCuO films to electromagnetic radiation. Solid State Communications, 76(4), 493–497.
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, S. V., Zakharov, A. A., Gershenzon, E. M., Gol'tsman, G. N., Ptitsyna, N. G., & Chulkova, G. M. (1990). AC losses and submillimeter absorption in single crystals La2CuO4. Phys. B Condens. Mat., 165-166, 1269–1270.
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, E. M., Gol'tsman, G. N., Potapov, V. D., & Sergeev, A. V. (1990). Restriction of microwave enhancement of superconductivity in impure superconductors due to electron-electron interaction. Solid State Communications, 75(8), 639–641.
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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Varyukhin, S. V., Zakharov, A. A., Gershenzon, E. M., Gol'tsman, G. N., Ptitsina, N. G., & Chulkova, G. M. (1990). Low energy excitation in La2CuO4. Sverkhprovodimost': Fizika, Khimiya, Tekhnika, 3(5), 832–837.
Abstract: Measurements of transmission and photoconductivity spectra in submillimeter wave length range as well as of capacity C and conductivity G in the region of acoustic frequencies of metal-dielectric-La2CuO4 system at low temperatures are performed using La2CuO4 monocrystals. Optical spectra posses a threshold character, a sharp decrease of transmission and photocoductivity signal occurs in the energy region hν>1.5 MeV. C(ω,T) and G(ω, T) dependences have a universal form typical of Debye type relaxation processes. Relaxation time dependence is of thermoactivated character τ(T)∼exp(ξ/T) with the gap value ξ≅2 meV. It is assumed that excitations with characteristic energy of ∼2 meV exist in La2CuO4. A possible nature of the detected low-energy excitations is discussed.
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Aksaev, E. E., Gershenzon, E. M., Gol'tsman, G. N., Semenov, A. D., & Sergeev, A. V. (1989). Interaction of electrons with thermal phonons in YBa2Cu3O7-δ films at low temperatures. JETP Lett., 50(5), 283–286.
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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Voevodin, E. I., Gershenzon, E. M., Goltsman, G. N., & Ptitsina, N. G. (1989). Energy-spectrum of shallow acceptors in Ge deformed strongly by a uniaxial pressure. Sov. Phys. and Technics of Semiconductors, 23(8), 843–846.
Abstract: Проведены исследования спектров фототермической ионизации мелких акцепторов (В, Аl) в Ge, предельно сжатом вдоль кристаллографической оси [100]. Из данных измерений с учетом теории построен энергетический спектр примесей. Показано, что энергии большого числа уровней четных и нечетных состояний хорошо соответствуют расчету, выполненному для примесей в анизотропном полупроводнике с параметром анизотропии γ=m∗⊥/m∗∥>1.
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Gershenzon, E. M., Gol’tsman, G. N., Sergeev, A., & Semenov, A. D. (1990). Picosecond response of YBaCuO films to electromagnetic radiation. In W. Gorzkowski, M. Gutowski, A. Reich, & H. Szymczak (Eds.), Proc. European Conf. High-Tc Thin Films and Single Crystals (pp. 457–462).
Abstract: Radiation-induced change of the resistance was studied in the resistive state of YBaCuO films. Electron-phonon relaxation time T h was determmed from direct ep measurements and analysis of quasistationary electron heating. Temperature dependence of That TS 40 K was found to – ep be T h.. T'. The resul ts show that ep detectors with the response time of few picosecond at nitrogen temperature can be realized.
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Gershenzon, E. M., Gershenson, M. E., Goltsman, G. N., Lyulkin, A. M., Semenov, A. D., & Sergeev, A. V. (1989). Limiting characteristics of fast-response superconducting bolometers. Zhurnal Tekhnicheskoi Fiziki, 59(2), 11–120.
Abstract: Теоретически и экспериментально исследовано физическое ограничение быстродействия сверхпроводящего болометра. Показано, что минимальная постоянная времени реализуется в условиях электронного разогрева и определяется процессом неупругого электрон-фонон-ного взаимодействия. Сформулированы требования к конструкции «электронного болометра» для достижения предельной чувствительности. Проведено сравнение характеристик электронного болометра и обычных болометров различных типов.
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Gershenzon, E. M., Gol'tsman, G. N., Elant'ev, A. I., Karasik, B. S., & Potoskuev, S. E. (1988). Intense electromagnetic radiation heating of superconductor electrons in resistive state. Fizika Nizkikh Temperatur, 14(7), 753–763.
Abstract: An experimental study is made of the effect of intense radiation in the millimeter and submillimeter ranges on thin and narrow Nb films in the resistive state. It is found that the excess resistance resulting from radiation and the dependence of its relaxation time on radiation intensity and transport current can be explained in terms of the effect of electron heating. Quantitative agreement is obtained between the experimental data and a homogeneous electron heating model.
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Gershenzon, E. M., Gol'tsman, G. N., Karasik, B. S., & Semenov, A. D. (1987). Measurement of the energy gap in the compound YBaCu3O9-δ on the basis of the IR absorption spectrum. JETP Lett., 46(5), 237–238.
Abstract: For the first time the long-wave infrared absorption spectrum has been measured by means of the bolometric effect and energy gap for high-temperature superconducting ceramics YBa/sub 2/Cu/sub 3/O/sub 9-delta/ has been determined from absorption threshold. 2delta/kT/sub c/ value is equal to 0.6.
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Gershenzon, E. M., Gershenzon, M. E., Gol'tsman, G. N., Karasik, B. S., Semenov, A. D., & Sergeev, A. V. (1987). Light-induced heating of electrons and the time of the inelastic electron-phonon scattering in the YBaCuO compound. JETP Lett., 46(6), 285–287.
Abstract: For the first time, measurements have been made on the electron energy relaxation time due to the electron--phonon interaction in films of the YBaCuO superconductor. The results indicate a significant intensification of the electron--phonon interaction in this compound as compared with normal superconducting metals.
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Gershenzon, E. M., Gol'tsman, G. N., Ptitsina, N. G., & Riger, E. R. (1986). Effect of electron-electron collisions on the trapping of free carriers by shallow impurity centers in germanium. Sov. Phys. JETP, 64(4), 889–897.
Abstract: Cascade Auger recombination of free carriers on shallow impurities in Ge is investigated under quasi-equilibrium conditions (T= 2-12 K) and in impurity breakdown. The Auger capture cross sections are found to be a,= 5. 10-l9 T-'n cm2 for donors and uip= 7- T-5p cm2 for acceptors. It is shown that in an isotropic semiconductor (p-Ge) ui is well described by the cascade-capture theory that takes into account only electron-electron collisions. In an anisotropic semiconductor ui is considerably larger (n-Ge, strongly uniaxially compressedp-Ge). Under impurity breakdown conditions the electron-electron collisions determine the lifetimes of the free carriers only in samples with appreciable density of the compensating impurity (Nk loi3 cmP3).
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Gershenzon, E. M., Gol'tsman, G. N., & Ptitsina, N. G. (1972). Observation of the free-exciton spectrum at submillimeter wavelengths. JETP Lett., 16(4), 161–162.
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