Le Touquet – Paris-Plage, France
Le Touquet – Paris-Plage, France

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Berdiyorov G.,Loughborough University | Berdiyorov G.,Qatar Environment and Energy Research Institute | Harrabi K.,King Fahd University of Petroleum and Minerals | Maneval J.P.,Laboratoire Pierre Aigrain | Peeters F.M.,University of Antwerp
Superconductor Science and Technology | Year: 2015

Using the anisotropic time-dependent Ginzburg-Landau theory we study the effect of ordered and disordered pinning on the time response of superconducting strips to an external current that switched on abruptly. The pinning centers result in a considerable delay of the response time of the system to such abrupt switching on of the current, whereas the output voltage is always larger when pinning is present. The resistive state in both cases are characterized either by dynamically stable phase-slip centers/lines or expanding in-time hot-spots, which are the main mechanisms for dissipation in current-carrying superconductors. We find that hot-spots are always initiated by the phase-slip state. However, the range of the applied current for the phase-slip state increases significantly when pinning is introduced. Qualitative changes are observed in the dynamics of the superconducting condensate in the presence of pinning. © 2015 IOP Publishing Ltd.

Estienne B.,University Pierre and Marie Curie | Regnault N.,Laboratoire Pierre Aigrain | Santachiara R.,University Paris - Sud
Nuclear Physics B | Year: 2010

Recently, Jack polynomials have been proposed as natural generalizations of Zk Read-Rezayi states describing non-Abelian fractional quantum Hall systems. These polynomials are conjectured to be related to correlation functions of a class of W-conformal field theories based on the Lie algebra Ak - 1. These theories can be considered as non-unitary solutions of a more general series of CFTs with Zk symmetry, the parafermionic theories. Starting from the observation that some parafermionic theories admit unitary solutions as well, we show, by computing the corresponding correlation functions, that these theories provide trial wavefunctions which satisfy the same clustering properties as the non-unitary ones. We show explicitly that, although the wavefunctions constructed by unitary CFTs cannot be expressed as a single Jack polynomial, they still show a fine structure where the mathematical properties of the Jack polynomials play a major role. © 2009 Elsevier B.V. All rights reserved.

Berdiyorov G.,Loughborough University | Berdiyorov G.,King Fahd University of Petroleum and Minerals | Harrabi K.,King Fahd University of Petroleum and Minerals | Oktasendra F.,King Fahd University of Petroleum and Minerals | And 4 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2014

Phase-slip centers/lines and hot spots are the main mechanisms for dissipation in current-carrying superconducting thin films. The pulsed-current method has recently been shown to be an effective tool in studying the dynamics of phase-slip centers and their evolution to hot spots. We use the time-dependent Ginzburg-Landau theory in the study of the dynamics of the superconducting condensate in superconducting strips under external current and zero external magnetic field. We show that both the flux-flow state (i.e., slow-moving vortices) and the phase-slip line state (i.e., fast-moving vortices) are dynamically stable dissipative units with temperature smaller than the critical one, whereas hot spots, which are localized normal regions where the local temperature exceeds the critical value, expand in time, resulting ultimately in a complete destruction of the condensate. The response time of the system to abrupt switching on of the overcritical current decreases with increasing both the value of the current (at all temperatures) and temperature (for a given value of the applied current). Our results are in good qualitative agreement with experiments we have conducted on Nb thin strips. © 2014 American Physical Society.

Grenier C.H.,University of Lyon | Herve R.,Laboratoire Pierre Aigrain | Bocquillon E.,Laboratoire Pierre Aigrain | Parmentier F.D.,Laboratoire Pierre Aigrain | And 4 more authors.
New Journal of Physics | Year: 2011

We propose a quantum tomography protocol to measure singleelectron coherence in quantum Hall edge channels, and therefore access for the first time the wavefunction of single-electron excitations propagating in ballistic quantum conductors. Its implementation would open the way to quantitative studies of single-electron decoherence and would provide a quantitative tool for analyzing single- to few-electron sources. We show how this protocol could be implemented using ultrahigh-sensitivity noise measurement schemes. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

Bowlan P.,Max Born Institute For Nichtlineare Optik Und Kurzzeitspektroskopie | Kuehn W.,Max Born Institute For Nichtlineare Optik Und Kurzzeitspektroskopie | Reimann K.,Max Born Institute For Nichtlineare Optik Und Kurzzeitspektroskopie | Woerner M.,Max Born Institute For Nichtlineare Optik Und Kurzzeitspektroskopie | And 3 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

Charge transport in an electron-hole plasma driven by high-field terahertz (THz) pulses is strongly influenced by electron-hole interactions, as has been shown in a recent publication. We introduce a picture of high-field THz transport which accounts for the roles of both types of carriers including their interactions. While holes make a negligible contribution to the current, they are heated by absorbing energy from the driving THz field and introduce a friction force for the electrons over a period of about 500 fs. Our model uses an extended version of the loss-function concept to calculate the time-dependent friction. The local field that drives the electrons differs from the incident THz field by screening due to Coulomb correlations in the plasma. We illustrate how spatial correlations between charged particles (electrons, holes, impurities) create a significant local-field correction to the THz driving field. The dominant contribution stems from Coulomb-correlated heavy-hole wave packets, which are strongly polarizable via inter-valence-band transitions. © 2012 American Physical Society.

Bennaceur K.,CEA Saclay Nuclear Research Center | Jacques P.,CEA Saclay Nuclear Research Center | Portier F.,CEA Saclay Nuclear Research Center | Roche P.,CEA Saclay Nuclear Research Center | And 2 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

The quantum Hall effect is universal and expected to occur in all two-dimensional electron systems in perpendicular high-magnetic field. We revisit quantum localization thanks to the high-energy scale of the quantum Hall effect in graphene, where the electron dynamics obey the Dirac equation. We solve a long debated question on the nature of electron transport in the transition region between Hall resistance plateaus. Is it of metallic or of variable-range hopping type as proposed, respectively, by Pruisken and Polyakov-Shklovskii? To the best of our knowledge, no experiment was able to discriminate between these models. Here, measurements of the conductance peak width scaling exponents with both temperature and current and determination of the localization length validates the variable-range hopping scenario. This shows that the usual assumption of a metallic behavior of the two-dimensional electron gas (2DEG) between Hall resistance plateaus is unnecessary for macroscopic samples. © 2012 American Physical Society.

Penillard A.,Paris West University Nanterre La Défense | Tripon-Canseliet C.,Paris West University Nanterre La Défense | Maksimovic I.,Paris West University Nanterre La Défense | Rosticher M.,Laboratoire Pierre Aigrain | And 3 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

A great interest has been lately initiated in the optoelectronics field for 2D materials with a tunable bandgap. Being able to choose the bandgap of a material is a huge progress in optoelectronics, since it would permit to overcome the limitation imposed by the graphene lack of energy bandgap, but also the restriction imposed by already used semiconductor whose bandgap are fixed and cannot apply for IR-NIR applications. From DFT simulations predictions, Black Phosphorus (bP) becomes a bidimensional semiconducting material with a direct tunable energy bandgap from 0.3 eV to 2 eV by controlling number of layers. This material also has a picosecond carrier response and exceptional mobilities under external excitation. Hence black phosphorus is a promising 2D material candidate for photoconductive switching under a NIR optical excitation as in telecommunication wavelength range of 1.55 μm. In this paper, material electromagnetic properties analysis is described in a large frequency band from optical to microwave measurements executed on different samples allowing energy bandgap and work function dependency to fabrication techniques, anisotropy and multiscale optoelectronic device realization by switch contact engineering and material passivation or encapsulation. Material implementation in microwave devices opens the route to new broadband electronic functionalities triggered by optics, thanks to light/matter extreme confinement degree. In this paper we present fabrication method of bP based microwave photoconductive switch, with a focus on black phosphorus Raman characterization, and obtained performances. © 2016 SPIE.

Harrabi K.,King Fahd University of Petroleum and Minerals | Harrabi K.,Laboratoire Pierre Aigrain
Journal of Superconductivity and Novel Magnetism | Year: 2013

In a superconducting microbridge too narrow to support vortex motion, the current-induced resistance occurs non-uniformly at definite spots designated as Phase-Slip-Centres (PSC). Further, if the core of a PSC happens to heat above the critical temperature Tc, a PSC may evolve into a normal propagating zone, or hotspot. The PSC's time of nucleation and the HS minimum current Ih are determined, which allows deriving without ambiguity the rate of heat transfer to the substrate, the latter is compatible with a phonon blackbody radiation model at the Nb/R-sapphire interface. The computation of the HS temperature is then straightforward, while the PSC case is more involved. However, the PSC core temperature can be obtained through an independent determination of the inelastic quasi-particle diffusion length Λqp∼2.8 μm. The results of these computations are consistent with all the specific cases, PSCs and HSs, measured experimentally. © 2013 Springer Science+Business Media New York.

Hemamouche A.,CNRS Laboratory for Photonics and Nanostructures | Morin A.,CNRS Laboratory for Photonics and Nanostructures | Bourhis E.,CNRS Laboratory for Photonics and Nanostructures | Toury B.,CNRS Materials Sciences and Technologies Laboratory | And 14 more authors.
Microelectronic Engineering | Year: 2014

Fabrication of nanopores and nanomasks has recently emerged as an area of considerable interest for research applications ranging from optics, to electronics and to biophysics. In this work we evaluate and compare the fabrication of nanopores, using a finely focused gallium beam, in free-standing membranes/films made of Si, SiN, and SiO2 (having thicknesses of a few tens of nanometers) and also in graphene and hexagonal boron nitride (h-BN) atomically thin suspended sheets. Mechanical resistance, charging effects and patterning performances are evaluated and compared. In spite of the very different properties of the membranes we report that reproducible nanopore fabrication in the sub-10 nm range can be achieved in both amorphous and atomically thin sheets using Ga+ focused ion beams (FIB). © 2014 Elsevier B.V. All rights reserved.

Harrabi K.,King Fahd University of Petroleum and Minerals | Salem A.F.,King Fahd University of Petroleum and Minerals | Ziq K.,King Fahd University of Petroleum and Minerals | Mansour A.I.,King Fahd University of Petroleum and Minerals | And 3 more authors.
Applied Physics A: Materials Science and Processing | Year: 2014

For over a decade, ultrathin superconducting films have been developed for the detection of single photons at optical or near infrared frequencies, with competitive performances in terms of quantum efficiency, speed, and low dark count rate. In order to avoid the requirement of helium refrigeration, we consider here the use of high temperature materials, known to achieve very fast responsiveness to laser irradiation. We excite thin filaments of the cuprate YBa2Cu3O7 by rectangular pulses of supercritical current so as to produce either a phase-slip centre (PSC) or a normal hot spot (HS), according to the temperature and the current amplitude selected. That procedure provides information about the maximum bias current to be used in a particle detector, about the return current back to the quiescent state after excitation, and about the rate of growth and decay of a HS. We also measure the time of PSC nucleation. A unique feature of that approach is to provide the rate of heat transfer between the film and its substrate at whatever temperature, in the superconducting state, in the practical conditions of operation. © 2014, Springer-Verlag Berlin Heidelberg.

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