Sidorova, M. V., Kozorezov, A. G., Semenov, A. V., Korneev, A. A., Chulkova, G. M., Korneeva, Y. P., et al. (2018). Non-bolometric bottleneck in electron-phonon relaxation in ultra-thin WSi film. arXiv:1607.07321v4 [physics.ins-det].
Abstract: We developed the model of the internal phonon bottleneck to describe the energy exchange between the acoustically soft ultrathin metal film and acoustically rigid substrate. Discriminating phonons in the film into two groups, escaping and nonescaping, we show that electrons and nonescaping phonons may form a unified subsystem, which is cooled down only due to interactions with escaping phonons, either due to direct phonon conversion or indirect sequential interaction with an electronic system. Using an amplitude-modulated absorption of the sub-THz radiation technique, we studied electron-phonon relaxation in ultrathin disordered films of tungsten silicide. We found an experimental proof of the internal phonon bottleneck. The experiment and simulation based on the proposed model agree well, resulting in tau{e-ph} = 140-190 ps at TC = 3.4 K, supporting the results of earlier measurements by independent techniques.
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Arutyunov, K. Y., Ramos-Álvarez, A., Semenov, A. V., Korneeva, Y. P., An, P. P., Korneev, A. A., et al. (2016). Quasi-1-dimensional superconductivity in highly disordered NbN nanowires. arXiv:1602.07932v1 [cond-mat.supr-con].
Abstract: The topic of superconductivity in strongly disordered materials has attracted a significant attention. In particular vivid debates are related to the subject of intrinsic spatial inhomogeneity responsible for non-BCS relation between the superconducting gap and the pairing potential. Here we report experimental study of electron transport properties of narrow NbN nanowires with effective cross sections of the order of the debated inhomogeneity scales. We find that conventional models based on phase slip concept provide reasonable fits for the shape of the R(T) transition curve. Temperature dependence of the critical current follows the text-book Ginzburg-Landau prediction for quasi-one-dimensional superconducting channel Ic~(1-T/Tc)^3/2. Hence, one may conclude that the intrinsic electronic inhomogeneity either does not exist in our structures, or, if exist, does not affect their resistive state properties.
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Arutyunov, K. Y., Ramos-Alvarez, A., Semenov, A. V., Korneeva, Y. P., An, P. P., Korneev, A. A., et al. (2016). Superconductivity in highly disordered NbN nanowires. Nanotechnol., 27(47), 47lt02 (1 to 8).
Abstract: The topic of superconductivity in strongly disordered materials has attracted significant attention. These materials appear to be rather promising for fabrication of various nanoscale devices such as bolometers and transition edge sensors of electromagnetic radiation. The vividly debated subject of intrinsic spatial inhomogeneity responsible for the non-Bardeen-Cooper-Schrieffer relation between the superconducting gap and the pairing potential is crucial both for understanding the fundamental issues of superconductivity in highly disordered superconductors, and for the operation of corresponding nanoelectronic devices. Here we report an experimental study of the electron transport properties of narrow NbN nanowires with effective cross sections of the order of the debated inhomogeneity scales. The temperature dependence of the critical current follows the textbook Ginzburg-Landau prediction for the quasi-one-dimensional superconducting channel I c approximately (1-T/T c)(3/2). We find that conventional models based on the the phase slip mechanism provide reasonable fits for the shape of R(T) transitions. Better agreement with R(T) data can be achieved assuming the existence of short 'weak links' with slightly reduced local critical temperature T c. Hence, one may conclude that an 'exotic' intrinsic electronic inhomogeneity either does not exist in our structures, or, if it does exist, it does not affect their resistive state properties, or does not provide any specific impact distinguishable from conventional weak links.
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Lobanov, Y. V., Shcherbatenko, M. L., Semenov, A. V., Kovalyuk, V. V., Korneev, A. A., Goltsman, G. N., et al. (2017). Heterodyne spectroscopy with superconducting single-photon detector. In EPJ Web Conf. (Vol. 132, 01005).
Abstract: We demonstrate successful operation of a Superconducting Single Photon Detector (SSPD) as the core element in a heterodyne receiver. Irradiating the SSPD by both a local oscillator power and signal power simultaneously, we observed beat signal at the intermediate frequency of a few MHz. Gain bandwidth was found to coincide with the detector single pulse width, where the latter depends on the detector kinetic inductance, determined by the superconducting nanowire length.
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Tarkhov, M., Claudon, J., Poizat, J. P., Korneev, A., Divochiy, A., Minaeva, O., et al. (2008). Ultrafast reset time of superconducting single photon detectors. Appl. Phys. Lett., 92(24), 241112 (1 to 3).
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