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Mooij, J. E., & Dekker, P. (1978). Static properties of two- and three-dimensional superconducting constrictions. J. Low Temp. Phys., 33(5/6), 551–576.
Abstract: Calculations have been performed on superconducting constrictions with hyperbolic geometry. Stationary Ginzburg-Landau equations are used, neglecting magneticfields. Emphasis is placed on the difference between two-and three -dimensional constrictions, which is related to the difference between uniform-thickness (UT) and variable-thickness (VT) superconducting microbridges. The width of the constriction w, normalized to the coherence length ξ is indicated by the parameter A (â‰<192> w/2ξ). It is found that small (A < 0.1), three-dimensional constrictions and VT bridges have a sinusoidal current-phase relation, linear temperature dependence of the critical current I c, and an I cR product (Ris the normal state resistance) equal to the Ambegaokar-Baratoff expression for Josephson junctions near T c. Two-dimensional constrictions behave as if they consist of an inner core with junction properties, in series with the films on both sides. The core consists of the region within a coherence length from the center of the structure. This size is temperature dependent. The core shows a sinusoidal current-phase relation and IcR according to Ambegaokar and Baratoff. For the whole constriction neither the phase difference nor R is finite. Two-dimensional constrictions have linear temperature dependence only when they are extremely narrow (A < 0.001). In two-dimensionalbridges the order parameter is depressed cover a distance of approximately the coherence length; in small three-dimensional constrictions this distance is approximately equal to the width. In narrow constrictions (and short microbridges) the current is not homogeneously distributedover the cross section. The effect has been investigated that occurs when in three-dimensional constrictions the width w is not much larger than l 0, the electron mean free path in the basic material. To this purpose a Ginzburg-Landau equation is derived from the Zaitsev boundary conditions which is valid for continuously changing material parameters. The critical current is decreased, but the IcR product remains constant.The results of the calculations are compared with experimental results for superconducting microbridges.
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Maslennikov, S. (2014). RF heating efficiency of the terahertz superconducting hot-electron bolometer. arXiv, 1404.5276, arXiv:1404.5276. Retrieved July 4, 2024, from http://arxiv.org/abs/1404.5276
Abstract: We report results of the numerical solution by the Euler method of the system of heat balance equations written in recurrent form for the superconducting hot-electron bolometer (HEB) embedded in an electrical circuit. By taking into account the dependence of the HEB resistance on the transport current we have been able to calculate rigorously the RF heating efficiency, absorbed local oscillator (LO) power and conversion gain of the HEB mixer. We show that the calculated conversion gai nis in excellent agreement with the experimental results, and that the substitution of the calculated RF heating efficiency and absorbed LO power into the expressions for the conversion gain and noise temperature given by the analytical small-signal model of the HEB yields excellent agreement with the corresponding measured values
Keywords: superconducting hot-electron bolometer mixer, HEB, NbN, distributed model, HEB model, HEB mixer model, heat balance equa-tions, conversion gain, RF heating efficiency, noise temperature, simulation, Euler method
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Beck, M., Klammer, M., Rousseau, I., Gol’tsman, G. N., Diamant, I., Dagan, Y., et al. (2015). Probing superconducting gap dynamics with THz pulses. In CLEO (SM3H.3 (1 to 2)). Optical Society of America.
Abstract: We studied superconducting gap dynamics in a BCS superconductor NbN and electron doped cuprate superconductor PCCO following excitation with near-infrared (NIR) and narrow band THz pulses. Systematic studies on PCCO imply very selective electron-phonon coupling.
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Gershenzon, E. M., Gol'tsman, G. N., Semenov, A. D., & Sergeev, A. V. (1992). Heating of electrons in resistive state of superconducting films. Detectors, mixers and switches. In Progress in High Temperature Superconductivity (Vol. 32, pp. 190–195).
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Titova, N., Kardakova, A. I., Tovpeko, N., Ryabchun, S., Mandal, S., Morozov, D., et al. (2017). Slow electron–phonon cooling in superconducting diamond films. IEEE Trans. Appl. Supercond., 27(4), 1–4.
Abstract: We have measured the electron-phonon energy-relaxation time, τ eph , in superconducting boron-doped diamond films grown on silicon substrate by chemical vapor deposition. The observed electron-phonon cooling times vary from 160 ns at 2.70 K to 410 ns at 1.8 K following a T -2-dependence. The data are consistent with the values of τ eph previously reported for single-crystal boron-doped diamond films epitaxially grown on diamond substrate. Such a noticeable slow electron-phonon relaxation in boron-doped diamond, in combination with a high normal-state resistivity, confirms a potential of superconducting diamond for ultrasensitive superconducting bolometers.
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