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Author Tinkham, M.; Free, J. U.; Lau, C. N.; Markovic, N.
Title Hysteretic I–V curves of superconducting nanowires Type Journal Article
Year 2003 Publication Phys. Rev. B Abbreviated Journal
Volume 68 Issue Pages 134515(1 to 7)
Keywords MoGe nanowires, self-heating effect
Abstract Experimental I–V curves of superconducting MoGe nanowires show hysteresis for the thicker wires and none for the thinner wires. A rather quantitative account of these data for representative wires is obtained by numerically solving the one-dimensional heat flow equation to find a self-consistent distribution of temperature and local resistivity along the wire, using the measured linear resistance R(T) as input. This suggests that the retrapping current in the hysteretic I–V curves is primarily determined by heating effects, and not by the dynamics of phase motion in a tilted washboard potential as often assumed. Heating effects and thermal fluctuations from the low-resistance state to a high-resistance, quasinormal regime appear to set independent upper bounds for the switching current.
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Call Number Serial 918
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Author Shah, Nayana; Pekker, David; Goldbart, Paul M.
Title Inherent stochasticity of superconductor-resistor switching behavior in nanowires Type Journal Article
Year 2008 Publication Phys. Rev. Lett. Abbreviated Journal Phys. Rev. Lett.
Volume 101 Issue Pages 207001(1 to 4)
Keywords superconducting nanowires, phase-slip, self-heating effect, temperature profile
Abstract We study the stochastic dynamics of superconductive-resistive switching in hysteretic current-biased superconducting nanowires undergoing phase-slip fluctuations. We evaluate the mean switching time using the master-equation formalism, and hence obtain the distribution of switching currents. We find that as the temperature is reduced this distribution initially broadens; only at lower temperatures does it show the narrowing with cooling naively expected for phase slips that are thermally activated. We also find that although several phase-slip events are generally necessary to induce switching, there is an experimentally accessible regime of temperatures and currents for which just one single phase-slip event is sufficient to induce switching, via the local heating it causes.
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Notes Approved no
Call Number Serial 919
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Author Pothier, H.; Guéron, S.; Birge, Norman O.; Esteve, D.; Devoret, M. H.
Title Energy distribution function of quasiparticles in mesoscopic wires Type Journal Article
Year 1997 Publication Phys. Rev. Lett. Abbreviated Journal
Volume 79 Issue 18 Pages 3490-3493
Keywords tunnel probe, metallic nanowire, diffusive wire, diffusive nanowire
Abstract We have measured with a tunnel probe the energy distribution function of Landau quasiparticles in metallic diffusive wires connected to two reservoir electrodes, with an applied bias voltage. The distribution function in the middle of a 1.5-μm-long wire resembles the half sum of the Fermi distributions of the reservoirs. The distribution functions in 5-μm-long wires are more rounded, due to interactions between quasiparticles during the longer diffusion time across the wire. From the scaling of the data with the bias voltage, we find that the scattering rate between two quasiparticles varies as <c9><203a>–2, where <c9><203a> is the energy transferred.
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Notes Approved no
Call Number Serial 921
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Author Pekker, David; Shah, Nayana; Sahu, Mitrabhanu; Bezryadin, Alexey; Goldbart, Paul M.
Title Stochastic dynamics of phase-slip trains and superconductive-resistive switching in current-biased nanowires Type Journal Article
Year 2009 Publication Phys. Rev. B Abbreviated Journal
Volume 80 Issue Pages 214525 (1 to 17)
Keywords superconducting nanowire, phase-slip, order parameter, HEB distributed model, HEB model
Abstract Superconducting nanowires fabricated via carbon-nanotube templating can be used to realize and study quasi-one-dimensional superconductors. However, measurement of the linear resistance of these nanowires have been inconclusive in determining the low-temperature behavior of phase-slip fluctuations, both quantal and thermal. Thus, we are motivated to study the nonlinear current-voltage characteristics in current-biased nanowires and the stochastic dynamics of superconductive-resistive switching, as a way of probing phase-slip events. In particular, we address the question: can a single phase-slip event occurring somewhere along the wire—during which the order-parameter fluctuates to zero—induce switching, via the local heating it causes? We explore this and related issues by constructing a stochastic model for the time evolution of the temperature in a nanowire whose ends are maintained at a fixed temperature. We derive the corresponding master equation as a tool for evaluating and analyzing the mean switching time at a given value of current (smaller than the depairing critical current). The model indicates that although, in general, several phase-slip events are necessary to induce switching via a thermal runaway, there is indeed a regime of temperatures and currents in which a single event is sufficient. We carry out a detailed comparison of the results of the model with experimental measurements of the distribution of switching currents, and provide an explanation for the rather counterintuitive broadening of the distribution width that is observed upon lowering the temperature. Moreover, we identify a regime in which the experiments are probing individual phase-slip events, and thus offer a way of unearthing and exploring the physics of nanoscale quantum tunneling of the one-dimensional collective quantum field associated with the superconducting order parameter.
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Notes Recommended by Klapwijk Approved no
Call Number Serial 923
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Author Anthore, A.; Pothier, H.; Esteve, D.
Title Density of states in a superconductor carrying a supercurrent Type Journal Article
Year 2003 Publication Phys. Rev. Lett. Abbreviated Journal Phys. Rev. Lett.
Volume 90 Issue 12 Pages 127001 (1 to 4)
Keywords Usadel, superconducting nanowire
Abstract We have measured the tunneling density of states (DOS) in a superconductor carrying a supercurrent or exposed to an external magnetic field. The pair correlations are weakened by the supercurrent, leading to a modification of the DOS and to a reduction of the gap. As predicted by the theory of superconductivity in diffusive metals, we find that this effect is similar to that of an external magnetic field.
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Notes Recommended by Klapwijk Approved no
Call Number Serial 924
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