Records |
Author |
Arutyunov, K. Y.; Ramos-Alvarez, A.; Semenov, A. V.; Korneeva, Y. P.; An, P. P.; Korneev, A. A.; Murphy, A.; Bezryadin, A.; Gol'tsman, G. N. |
Title |
Superconductivity in highly disordered NbN nanowires |
Type |
Journal Article |
Year |
2016 |
Publication |
Nanotechnol. |
Abbreviated Journal |
Nanotechnol. |
Volume |
27 |
Issue |
47 |
Pages |
47lt02 (1 to 8) |
Keywords |
NbN nanowires |
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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National Research University Higher School of Economics, Moscow Institute of Electronics and Mathematics,109028, Moscow, Russia. P L Kapitza Institute for Physical Problems RAS, Moscow, 119334, Russia |
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English |
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0957-4484 |
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PMID:27782000 |
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no |
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1332 |
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Author |
Seliverstov, S. V.; Rusova, A. A.; Kaurova, N. S.; Voronov, B. M.; Goltsman, G. N. |
Title |
Attojoule energy resolution of direct detector based on hot electron bolometer |
Type |
Conference Article |
Year |
2016 |
Publication |
J. Phys.: Conf. Ser. |
Abbreviated Journal |
J. Phys.: Conf. Ser. |
Volume |
741 |
Issue |
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Pages |
012165 (1 to 5) |
Keywords |
NbN HEB detector |
Abstract |
We characterize superconducting antenna-coupled NbN hot-electron bolometer (HEB) for direct detection of THz radiation operating at a temperature of 9.0 K. At signal frequency of 2.5 THz, the measured value of the optical noise equivalent power is 2.0×10-13 W-Hz-0.5. The estimated value of the energy resolution is about 1.5 aJ. This value was confirmed in the experiment with pulsed 1.55-μm laser employed as a radiation source. The directly measured detector energy resolution is 2 aJ. The obtained risetime of pulses from the detector is 130 ps. This value was determined by the properties of the RF line. These characteristics make our detector a device-of-choice for a number of practical applications associated with detection of short THz pulses. |
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IOP Publishing |
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Seliverstov_2016 |
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1337 |
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Author |
Arutyunov, K. Y.; Ramos-Álvarez, A.; Semenov, A. V.; Korneeva, Y. P.; An, P. P.; Korneev, A. A.; Murphy, A.; Bezryadin, A.; Gol’tsman, G. N. |
Title |
Quasi-1-dimensional superconductivity in highly disordered NbN nanowires |
Type |
Miscellaneous |
Year |
2016 |
Publication |
arXiv |
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Pages |
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Keywords |
narrow NbN nanowires, BCS |
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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Duplicated as 1332 |
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1338 |
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Korneeva, Y.; Sidorova, M.; Semenov, A.; Krasnosvobodtsev, S.; Mitsen, K.; Korneev, A.; Chulkova, G.; Goltsman, G. |
Title |
Comparison of hot-spot formation in NbC and NbN single-photon detectors |
Type |
Journal Article |
Year |
2016 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
Volume |
26 |
Issue |
3 |
Pages |
1-4 |
Keywords |
NbC, NbN SSPD, SNSPD |
Abstract |
We report an experimental investigation of the hot-spot evolution in superconducting single-photon detectors made of disordered superconducting materials with different diffusivity and energy downconversion time values, i.e., 33-nm-thick NbN and 23-nm-thick NbC films. We have demonstrated that, in NbC film, only 405-nm photons produce sufficiently large hot spot to trigger a single-photon response. The dependence of detection efficiency on bias current for 405-nm photons in NbC is similar to that for 3400-nm photons in NbN. In NbC, large diffusivity and downconversion time result in 1-D critical current suppression profile compared with the usual 2-D profile in NbN. |
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1051-8223 |
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1348 |
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Author |
Tong, C.-Y. E.; Trifonov, A.; Shurakov, A.; Blundell, R.; Gol’tsman, G. |
Title |
A microwave-operated hot-electron-bolometric power detector for terahertz radiation |
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Journal Article |
Year |
2015 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
Volume |
25 |
Issue |
3 |
Pages |
2300604 (1 to 4) |
Keywords |
NbN HEB mixer |
Abstract |
A new class of microwave-operated THz power detectors based on the NbN hot-electron-bolometer (HEB) mixer is proposed. The injected microwave signal ( 1 GHz) serves the dual purpose of pumping the HEB element and enabling the read-out of the internal state of the device. A cryogenic amplifier amplifies the reflected microwave signal from the device and a homodyne scheme recovers the effects of the incident THz radiation. Two modes of operation have been identified, depending on the level of incident radiation. For weak signals, we use a chopper to chop the incident radiation against a black body reference and a lock-in amplifier to perform synchronous detection of the homodyne readout. The voltage measured is proportional to the incident power, and we estimate an optical noise equivalent power of 5pW/ √Hz at 0.83 THz. At higher signal levels, the homodyne circuit recovers the stream of steady relaxation oscillation pulses from the HEB device. The frequency of these pulses is in the MHz frequency range and bears a linear relationship with the incident THz radiation over an input power range of 15 dB. A digital frequency counter is used to measure THz power. The applicable power range is between 1 nW and 1 μW. |
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1558-2515 |
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1354 |
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