The characteristic electron–phonon coupling time of unconventional superconductors and implications for optical detectors

Parlato, L.; Latempa, R.; Peluso, G.; Pepe, Giovanni Piero; Cristiano, R.; Sobolewski, Roman

doi:10.1088/0953-2048/18/9/018

Cited by 30 publications

(20 citation statements)

References 40 publications

(56 reference statements)

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“…25,26 It is also worth mentioning that even if the values of τ E obtained for the NbN device are higher compared to those estimated from photoresponse experiments, the scaling between the characteristic times of NbN and Nb is consistent with that reported in Ref. 31. The disagreement in the numbers obtained for τ E is probably due to the different techniques applied to investigate the electron relaxation dynamics as a consequence of different excitation energies.…”

Section: B Energy Relaxation Timessupporting

confidence: 81%

“…It is well known, in fact, that NbN guarantees a fast energy relaxation process due to the extremely reduced characteristic electronphonon (e-ph) coupling time. 31 Moreover, this material is characterized by a short coherence length, which assures that a relatively high superconducting critical temperature T c can be obtained even for thicknesses of a few nanometers, so that NbN ultrathin films can have high single-photon sensitivity. The choice of the ferromagnetic materials is also extremely important, since it can strongly influence the critical temperature and the quasiparticle relaxation process of the system.…”

Section: Introductionmentioning

confidence: 99%

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Quasiparticle energy relaxation times in NbN/CuNi nanostripes from critical velocity measurements

et al. 2011

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The dynamic instability of the moving vortex lattice at high driving currents in NbN/CuNi-based and NbN nanostripes designed for optical detection has been studied. By applying the model proposed by Larkin and Ovchinnikov [Zh. Eksp. Teor. Fiz. 68, 1915 (1975)], from the critical velocity v ∗ for the occurrence of the instability, it was possible to estimate the values of the quasiparticle relaxation times τE. The results show that the NbN/CuNi-based devices are characterized by shorter values of τE compared to that of NbN

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Section: B Energy Relaxation Timessupporting

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Quasiparticle energy relaxation times in NbN/CuNi nanostripes from critical velocity measurements

et al. 2011

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“…In addition, MgB 2 is a unique two-gap superconductor with the smaller gap (∼2 meV) comparable to that of NbN, 8 which is expected to ensure its optical detection properties such as the detectable spectrum range not deteriorated. Moreover, it has been noted that the electron-phonon coupling time τ 0 in MgB 2 (∼2 ps) is much shorter than that in NbN, 9 responses of the devices. All these features have combined to make the fabrication of MgB 2 -based HEBs or SSPDs rather attractive.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of superconducting nanowires from ultrathin MgB2 films via focused ion beam milling

et al. 2015

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High quality superconducting nanowires were fabricated from ultrathin MgB2 films by a focused ion beam milling technique. The precursor MgB2 films in 10 nm thick were grown on MgO substrates by using a hybrid physical-chemical vapor deposition method. The nanowires, in widths of about 300-600 nm and lengths of 1 or 10 μm, showed high superconducting critical temperatures (Tc’s) above 34 K and narrow superconducting transition widths (ΔTc’s) of 1-3 K. The superconducting critical current density Jc of the nanowires was above 5 × 107 A/cm2 at 20 K. The high Tc, narrow ΔTc, and high Jc of the nanowires offered the possibility of making MgB2-based nano-devices such as hot-electron bolometers and superconducting nanowire single-photon detectors with high operating temperatures at 15-20 K.

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“…Their time performances are related to the electron-phonon scattering time as discussed in Ref. [9]. Some nitrides, and in particular NbN and TiN, show very fast times (τ 0 ~ few ps): in particular, NbN has been already investigated for SSPDs showing τ e-ph ≅ 10 ps [10].…”

Section: / 3 ( / )mentioning

confidence: 99%

Superconductive radiation detectors: challenges and some recent achievements

Barone¹,

Ejrnes

Esposito

et al. 2006

Phys. Status Solidi (c)

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The interest of superconductor materials for the realization of radiation detectors lies in a variety of concrete achievements and stimulating proposals. In this paper, recent aspects of superconductive radiation detectors are reviewed wich refer to two important issues. The former deals with results concerning detectors based on superconductive junctions in a configuration which provide both energy and time discrimination of single photons. The latter concerns materials and device aspects of hot-electron photodetectors based on nanosized heterostructured superconducting strips. Both aspects offer a new potential in the field of radiation detection.1 Introduction Superconductors are materials with potential for radiation detection applications, due to their high-energy sensitivity over a very wide frequency range (from X-ray to mm-millimeter wavelengths), ultrafast electronic response times (down to few ps), and radiation hardness. The superconductor response to the radiation interaction involves a complex dynamics which depends on the relaxation processes involving phonons, quasiparticles, and Cooper pairs during the energy cascade, following absorption of radiation quanta in the superconductor. The mean energy ε needed to create an excitation, i.e., two quasiparticles by breaking a Cooper pair, is of the order of the superconductor energy gap ∆ (order of 1 meV), and hence three orders of magnitude smaller than that in a typical semiconductor. This implies that for a given energy ∆Ε released by the impinging radiation, the number of produced excitations is drastically higher leading to a significant increase of the energy resolution. Of paramount importance is also the "time resolution" which can be reached with proper superconductive structure configurations. In the next section it will be discussed a concrete example in which a precious merging of energy and time detection is realized combining a superconductive tunnel junction (STJ) and a Josephson Junction (JJ). Section 3 deals with basic issues concerning the physics and material aspects of superconductive hot-electron photodetectors (HEPs) based on nanostructured strip. Detectors of this kind can provide ultrafast photon counting. Results of femtosecond pump-probe experiments are reported. Brief concluding remarks are finally reported.

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The characteristic electron–phonon coupling time of unconventional superconductors and implications for optical detectors

Cited by 30 publications

References 40 publications

Quasiparticle energy relaxation times in NbN/CuNi nanostripes from critical velocity measurements

Quasiparticle energy relaxation times in NbN/CuNi nanostripes from critical velocity measurements

Fabrication of superconducting nanowires from ultrathin MgB2 films via focused ion beam milling

Superconductive radiation detectors: challenges and some recent achievements

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