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Author Sidorova, M.; Semenov, Alexej D.; Hübers, H.-W.; Ilin, K.; Siegel, M.; Charaev, I.; Moshkova, M.; Kaurova, N.; Goltsman, G. N.; Zhang, X.; Schilling, A.
Title Electron energy relaxation in disordered superconducting NbN films Type Journal Article
Year 2020 Publication (up) Phys. Rev. B Abbreviated Journal Phys. Rev. B
Volume 102 Issue 5 Pages 054501 (1 to 15)
Keywords NbN SSPD, SNSPD, HEB, bandwidth, relaxation time
Abstract We report on the inelastic-scattering rate of electrons on phonons and relaxation of electron energy studied by means of magnetoconductance, and photoresponse, respectively, in a series of strongly disordered superconducting NbN films. The studied films with thicknesses in the range from 3 to 33 nm are characterized by different Ioffe-Regel parameters but an almost constant product qTl (qT is the wave vector of thermal phonons and l is the elastic mean free path of electrons). In the temperature range 14–30 K, the electron-phonon scattering rates obey temperature dependencies close to the power law 1/τe−ph∼Tn with the exponents n≈3.2–3.8. We found that in this temperature range τe−ph and n of studied films vary weakly with the thickness and square resistance. At 10 K electron-phonon scattering times are in the range 11.9–17.5 ps. The data extracted from magnetoconductance measurements were used to describe the experimental photoresponse with the two-temperature model. For thick films, the photoresponse is reasonably well described without fitting parameters, however, for thinner films, the fit requires a smaller heat capacity of phonons. We attribute this finding to the reduced density of phonon states in thin films at low temperatures. We also show that the estimated Debye temperature in the studied NbN films is noticeably smaller than in bulk material.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9950 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1266
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Author Sidorova, M. V.; Kozorezov, A. G.; Semenov, A. V.; Korneeva, Y. P.; Mikhailov, M. Y.; Devizenko, A. Y.; Korneev, A. A.; Chulkova, G. M.; Goltsman, G. N.
Title Nonbolometric bottleneck in electron-phonon relaxation in ultrathin WSi films Type Journal Article
Year 2018 Publication (up) Phys. Rev. B Abbreviated Journal Phys. Rev. B
Volume 97 Issue 18 Pages 184512 (1 to 13)
Keywords WSi films, diffusion constant, SSPD, SNSPD
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 τe−ph∼140–190 ps at TC=3.4K, supporting the results of earlier measurements by independent techniques.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9950 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1305
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Author Vodolazov, D. Y.; Korneeva, Y. P.; Semenov, A. V.; Korneev, A. A.; Goltsman, G. N.
Title Vortex-assisted mechanism of photon counting in a superconducting nanowire single-photon detector revealed by external magnetic field Type Journal Article
Year 2015 Publication (up) Phys. Rev. B Abbreviated Journal Phys. Rev. B
Volume 92 Issue 10 Pages 104503 (1 to 9)
Keywords SSPD, SNSPD
Abstract We use an external magnetic field to probe the detection mechanism of a superconducting nanowire single-photon detector. We argue that the hot belt model (which assumes partial suppression of the superconducting order parameter Δ across the whole width of the superconducting nanowire after absorption of the photon) does not explain observed weak-field dependence of the photon count rate (PCR) for photons with λ=450nm and noticeable decrease of PCR (with increasing the magnetic field) in a range of the currents for photons with wavelengths λ=450–1200nm. Found experimental results for all studied wavelengths can be explained by the vortex hot spot model (which assumes partial suppression of Δ in the area with size smaller than the width of the nanowire) if one takes into account nucleation and entrance of the vortices to the photon induced hot spot and their pinning by the hot spot with relatively large size and strongly suppressed Δ.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1343
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Author Lusche, R.; Semenov, A.; Korneeva, Y.; Trifonov, A.; Korneev, A.; Gol'tsman, G.; Hübers, H.-W.
Title Effect of magnetic field on the photon detection in thin superconducting meander structures Type Journal Article
Year 2014 Publication (up) Phys. Rev. B Abbreviated Journal Phys. Rev. B
Volume 89 Issue 10 Pages 104513 (1 to 7)
Keywords NbN SSPD, SNSPD
Abstract We have studied the influence of an externally applied magnetic field on the photon and dark count rates of meander-type niobium nitride superconducting nanowire single-photon detectors. Measurements have been performed at a temperature of 4.2 K, and magnetic fields up to 250 mT have been applied perpendicularly to the meander plane. While photon count rates are field independent at weak applied fields, they show a strong dependence at fields starting from approximately ±25 mT. This behavior, as well as the magnetic field dependence of the dark count rates, is in good agreement with the recent theoretical model of vortex-assisted photon detection and spontaneous vortex crossing in narrow superconducting lines. However, the local reduction of the superconducting free energy due to photon absorption, which is the fitting parameter in the model, increases much slower with the photon energy than the model predicts. Furthermore, changes in the free-energy during photon counts and dark counts depend differently on the current that flows through the meander. This indicates that photon counts and dark counts occur in different parts of the meander.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1367
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Author Peltonen, J. T.; Astafiev, O. V.; Korneeva, Y. P.; Voronov, B. M.; Korneev, A. A.; Charaev, I. M.; Semenov, A. V.; Golt'sman, G. N.; Ioffe, L. B.; Klapwijk, T. M.; Tsai, J. S.
Title Coherent flux tunneling through NbN nanowires Type Journal Article
Year 2013 Publication (up) Phys. Rev. B Abbreviated Journal Phys. Rev. B
Volume 88 Issue 22 Pages 220506 (1 to 5)
Keywords NbN nanowires
Abstract We demonstrate evidence of coherent magnetic flux tunneling through superconducting nanowires patterned in a thin highly disordered NbN film. The phenomenon is revealed as a superposition of flux states in a fully metallic superconducting loop with the nanowire acting as an effective tunnel barrier for the magnetic flux, and reproducibly observed in different wires. The flux superposition achieved in the fully metallic NbN rings proves the universality of the phenomenon previously reported for InOx. We perform microwave spectroscopy and study the tunneling amplitude as a function of the wire width, compare the experimental results with theories, and estimate the parameters for existing theoretical models.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1369
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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 (up) Phys. Rev. B Abbreviated Journal Phys. Rev. B
Volume 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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Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1423
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Author Zhang, J.; Słysz, W.; Pearlman, A.; Verevkin, A.; Sobolewski, R.; Okunev, O.; Chulkova, G.; Gol’tsman, G. N.
Title Time delay of resistive-state formation in superconducting stripes excited by single optical photons Type Journal Article
Year 2003 Publication (up) Phys. Rev. B Abbreviated Journal Phys. Rev. B
Volume 67 Issue 13 Pages 132508 (1 to 4)
Keywords NbN SSPD, SNSPD
Abstract We have observed a 65(±5)-ps time delay in the onset of a resistive-state formation in 10-nm-thick, 130-nm-wide NbN superconducting stripes exposed to single photons. The delay in the photoresponse decreased to zero when the stripe was irradiated by multi-photon (classical) optical pulses. Our NbN structures were kept at 4.2 K, well below the material’s critical temperature, and were illuminated by 100-fs-wide optical pulses. The time-delay phenomenon has been explained within the framework of a model based on photon-induced generation of a hotspot in the superconducting stripe and subsequent, supercurrent-assisted, resistive-state formation across the entire stripe cross section. The measured time delays in both the single-photon and two-photon detection regimes agree well with theoretical predictions of the resistive-state dynamics in one-dimensional superconducting stripes.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0163-1829 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1519
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Author Il’in, K.S.; Ptitsina, N.G.; Sergeev, A.V.; Gol’tsman, G.N.; Gershenzon, E.M.; Karasik, B.S.; Pechen, E.V.; Krasnosvobodtsev, S.I.
Title Interrelation of resistivity and inelastic electron-phonon scattering rate in impure NbC films Type Journal Article
Year 1998 Publication (up) Phys. Rev. B Abbreviated Journal Phys. Rev. B
Volume 57 Issue 24 Pages 15623-15628
Keywords NbC films
Abstract A complex study of the electron-phonon interaction in thin NbC films with electron mean free path l=2–13nm gives strong evidence that electron scattering is significantly modified due to the interference between electron-phonon and elastic electron scattering from impurities. The interference T2 term, which is proportional to the residual resistivity, dominates over the Bloch-Grüneisen contribution to resistivity at low temperatures up to 60 K. The electron energy relaxation rate is directly measured via the relaxation of hot electrons heated by modulated electromagnetic radiation. In the temperature range 1.5–10 K the relaxation rate shows a weak dependence on the electron mean free path and strong temperature dependence ∼Tn, with the exponent n=2.5–3. This behavior is explained well by the theory of the electron-phonon-impurity interference taking into account the electron coupling with transverse phonons determined from the resistivity data.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0163-1829 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1585
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Author Ptitsina, N. G.; Chulkova, G. M.; Il’in, K. S.; Sergeev, A. V.; Pochinkov, F. S.; Gershenzon, E. M.; Gershenson, M. E.
Title Electron-phonon interaction in disordered metal films: The resistivity and electron dephasing rate Type Journal Article
Year 1997 Publication (up) Phys. Rev. B Abbreviated Journal Phys. Rev. B
Volume 56 Issue 16 Pages 10089-10096
Keywords disordered metal films, electron-phonon interaction, electron dephasing rate, resistivity
Abstract The temperature dependence of the resistance of films of Al, Be, and NbC with small values of the electron mean free path l=1.5–10nm has been measured at 4.2–300 K. The resistance of all the films contains a T2 contribution that is proportional to the residual resistance; this contribution has been attributed to the interference between the elastic electron scattering and the electron-phonon scattering. Fitting the data to the theory of the electron-phonon-impurity interference (M. Yu. Reiser and A. V. Sergeev, Zh. Eksp. Teor. Fiz. 92, 224 (1987) [Sov. Phys. JETP 65, 1291 (1987)]), we obtain constants of interaction of the electrons with transverse phonons, and estimate the contribution of this interaction to the electron dephasing rate in thin films of Au, Al, Be, Nb, and NbC. Our estimates are in a good agreement with the experimental data on the inelastic electron-phonon scattering in these films. This indicates that the interaction of electrons with transverse phonons controls the electron-phonon relaxation rate in thin-metal films over a broad temperature range.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0163-1829 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1766
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Author Zhang, X.; Lita, A. E.; Smirnov, K.; Liu, H. L.; Zhu, D.; Verma, V. B.; Nam, S. W.; Schilling, A.
Title Strong suppression of the resistivity near the superconducting transition in narrow microbridges in external magnetic fields Type Journal Article
Year 2020 Publication (up) Phys. Rev. B Abbreviated Journal Phys. Rev. B
Volume 101 Issue 6 Pages 060508 (1 to 6)
Keywords MoSi, WSi films
Abstract We have investigated a series of superconducting bridges based on homogeneous amorphous WSi and MoSi films, with bridge widths w ranging from 2 to 1000μm and film thicknesses d∼4−6 and 100 nm. Upon decreasing the bridge widths below the respective Pearl lengths, we observe in all cases distinct changes in the characteristics of the resistive transitions to superconductivity. For each of the films, the resistivity curves R(B,T) separate at a well-defined and field-dependent temperature T∗(B) with decreasing the temperature, resulting in a dramatic suppression of the resistivity and a sharpening of the transitions with decreasing bridge width w. The associated excess conductivity in all the bridges scales as 1/w, which may suggest either the presence of a highly conducting region that is dominating the electric transport, or a change in the vortex dynamics in narrow enough bridges. We argue that this effect can only be observed in materials with sufficiently weak vortex pinning.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9950 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1800
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Author Sidorova, M.; Semenov, A.; Hübers, H.-W.; Kuzmin, A.; Doerner, S.; Ilin, K.; Siegel, M.; Charaev, I.; Vodolazov, D.
Title Timing jitter in photon detection by straight superconducting nanowires: Effect of magnetic field and photon flux Type Journal Article
Year 2018 Publication (up) Phys. Rev. B Abbreviated Journal Phys. Rev. B
Volume 98 Issue 13 Pages 134504 (1 to 14)
Keywords SNSPD, NbN namowires
Abstract We studied the effects of the external magnetic field and photon flux on timing jitter in photon detection by straight superconducting NbN nanowires. At two wavelengths 800 and 1560 nm, statistical distribution in the appearance times of photon counts exhibits Gaussian shape at small times and an exponential tail at large times. The characteristic exponential time is larger for photons with smaller energy and increases with external magnetic field while variations in the Gaussian part of the distribution are less pronounced. Increasing photon flux drives the nanowire from the discrete quantum detection regime to the uniform bolometric regime that averages out fluctuations of the total number of nonequilibrium electrons created by the photon and drastically reduces jitter. The difference between standard deviations of Gaussian parts of distributions for these two regimes provides the measure for the strength of electron-number fluctuations; it increases with the photon energy. We show that the two-dimensional hot-spot detection model explains qualitatively the effect of magnetic field.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9950 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1842
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Author Sergeev, A.; Karasik, B. S.; Ptitsina, N. G.; Chulkova, G. M.; Il'in, K. S.; Gershenzon, E. M.
Title Electron–phonon interaction in disordered conductors Type Journal Article
Year 1999 Publication (up) Phys. Rev. B Condens. Matter Abbreviated Journal Phys. Rev. B Condens. Matter
Volume 263-264 Issue Pages 190-192
Keywords disordered conductors, electron-phonon interaction
Abstract The electron–phonon interaction is strongly modified in conductors with a small value of the electron mean free path (impure metals, thin films). As a result, the temperature dependencies of both the inelastic electron scattering rate and resistivity differ significantly from those for pure bulk materials. Recent complex measurements have shown that modified dependencies are well described at K by the electron interaction with transverse phonons. At helium temperatures, available data are conflicting, and cannot be described by an universal model.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0921-4526 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1765
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Author Verevkin, A. A.; Ptitsina, N. G.; Chulcova, G. M.; Gol'Tsman, G. N.; Gershenzon, E. M.; Yngvesson, K. S.
Title Determination of the limiting mobility of a two-dimensional electron gas in AlxGa1-xAs/GaAs heterostructures and direct measurement of the energy relaxation time Type Journal Article
Year 1996 Publication (up) Phys. Rev. B Condens. Matter. Abbreviated Journal Phys. Rev. B Condens. Matter.
Volume 53 Issue 12 Pages R7592-R7595
Keywords 2DEG, AlGaAs/GaAs heterostructures
Abstract We present results for a method to measure directly the energy relaxation time (τe) for electrons in a single AlxGa1−xAs/GaAs heterojunction; measurements were performed from 1.6 to 15 K under quasiequilibrium conditions. We find τeαT−1 below 4 K, and τe independent of T above 4 K. We have also measured the energy-loss rate, ⟨Q⟩, by the Shubnikov-de Haas technique, and find ⟨Q⟩α(T3e−T3) for T<~4.2 K; Te is the electron temperature. The values and temperature dependence of τe and ⟨Q⟩ for T<4 K agree with calculations based on piezoelectric and deformation potential acoustic phonon scattering. At 4.2 K, we can also estimate the momentum relaxation time, τm, from our measured τe. This leads to a preliminary estimate of the phonon-limited mobility at 4.2 K of μ=3×107 cm2/Vs (ns=4.2×1011 cm−2), which agrees well with published numerical calculations, as well as with an earlier indirect estimate based on measurements on a sample with much higher mobility.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0163-1829 ISBN Medium
Area Expedition Conference
Notes PMID:9982274 Approved no
Call Number Serial 1612
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Author Sergeev, A. V.; Semenov, A. D.; Kouminov, P.; Trifonov, V.; Goghidze, I. G.; Karasik, B. S.; Gol’tsman, G. N.; Gershenzon, E. M.
Title Transparency of a YBa2Cu3O7-film/substrate interface for thermal phonons measured by means of voltage response to radiation Type Journal Article
Year 1994 Publication (up) Phys. Rev. B Condens. Matter. Abbreviated Journal Phys. Rev. B Condens. Matter.
Volume 49 Issue 13 Pages 9091-9096
Keywords YBCO films
Abstract The transparency of a film/substrate interface for thermal phonons was investigated for YBa2Cu3O7 thin films deposited on MgO, Al2O3, LaAlO3, NdGaO3, and ZrO2 substrates. Both voltage response to pulsed-visible and to continuously modulated far-infrared radiation show two regimes of heat escape from the film to the substrate. That one dominated by the thermal boundary resistance at the film/substrate interface provides an initial exponential decay of the response. The other one prevailing at longer times or smaller modulation frequencies causes much slower decay and is governed by phonon diffusion in the substrate. The transparency of the boundary for phonons incident from the film on the substrate and also from the substrate on the film was determined separately from the characteristic time of the exponential decay and from the time at which one regime was changed to the other. Taking into account the specific heat of optical phonons and the temperature dependence of the group velocity of acoustic phonons, we show that the body of experimental data agrees with acoustic mismatch theory rather than with the model that assumes strong diffusive scattering of phonons at the interface.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0163-1829 ISBN Medium
Area Expedition Conference
Notes PMID:10009690 Approved no
Call Number Serial 1648
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Author Sergeev, A.; Mitin, V.
Title Electron-phonon interaction in disordered conductors: Static and vibrating scattering potentials Type Journal Article
Year 2000 Publication (up) Phys. Rev. B. Abbreviated Journal Phys. Rev. B.
Volume 61 Issue 9 Pages 6041-6047
Keywords disordered conductors, scattering potential, electron-phonon interaction
Abstract Employing the Keldysh diagram technique, we calculate the electron-phonon energy relaxation rate in a conductor with the vibrating and static δ-correlated random electron-scattering potentials. If the scattering potential is completely dragged by phonons, this model yields the Schmid’s result for the inelastic electron-scattering rate τ−1e−ph. At low temperatures the effective interaction decreases due to disorder, and τ−1e−ph∝T4l (l is the electron mean-free path). In the presense of the static potential, quantum interference of numerous scattering processes drastically changes the effective electron-phonon interaction. In particular, at low temperatures the interaction increases, and τ−1e−ph∝T2/l. Along with an enhancement of the interaction, which is observed in disordered metallic films and semiconducting structures at low temperatures, the suggested model allows us to explain the strong sensitivity of the electron relaxation rate to the microscopic quality of a particular film.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0163-1829 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 307
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