Superconductive Tunnelling and Applications

Solymár, L.; Douglass, D. H.

doi:10.1119/1.1987398

Cited by 113 publications

(97 citation statements)

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“…The resulting equations are then the familiar ones found in many reference books, such as Refs. 21,24,25,26,27,28,29. However, we are interested here in the case for which d < λ, such that the fields and currents are governed by the two-dimensional screening length or Pearl length…”

Section: Basic Equationsmentioning

confidence: 99%

Response of thin-film SQUIDs to applied fields and vortex fields: Linear SQUIDs

Clem

Brandt

2005

Phys. Rev. B

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In this paper we analyze the properties of a dc SQUID when the London penetration depth λ is larger than the superconducting film thickness d. We present equations that govern the static behavior for arbitrary values of Λ = λ 2 /d relative to the linear dimensions of the SQUID. The SQUID's critical current Ic depends upon the effective flux Φ, the magnetic flux through a contour surrounding the central hole plus a term proportional to the line integral of the current density around this contour. While it is well known that the SQUID inductance depends upon Λ, we show here that the focusing of magnetic flux from applied fields and vortex-generated fields into the central hole of the SQUID also depends upon Λ. We apply this formalism to the simplest case of a linear SQUID of width 2w, consisting of a coplanar pair of long superconducting strips of separation 2a, connected by two small Josephson junctions to a superconducting current-input lead at one end and by a superconducting lead at the other end. The central region of this SQUID shares many properties with a superconducting coplanar stripline. We calculate magnetic-field and current-density profiles, the inductance (including both geometric and kinetic inductances), magnetic moments, and the effective area as a function of Λ/w and a/w.

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Section: Basic Equationsmentioning

confidence: 99%

Response of thin-film SQUIDs to applied fields and vortex fields: Linear SQUIDs

Clem

Brandt

2005

Phys. Rev. B

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“…When E J becomes larger than k B T , * Email address: rdynes@ucsd.edu a supercurrent of magnitude I = I c,0 sin φ can flow across the junction at zero voltage [9]; here I c,0 = 2eE J /h and φ is the relative phase. When a finite voltage V is applied across the junction, φ oscillates according tȯ φ = 2eV /h.…”

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confidence: 99%

“…When a finite voltage V is applied across the junction, φ oscillates according tȯ φ = 2eV /h. These are the well known Josephson equations and the Josephson effect in low resistance junctions with macroscopically sized electrodes is well understood and well studied [9].…”

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confidence: 99%

“…In the absence of fluctuations, when E J ≫k B T, E C , a voltage source driven Josephson junction exhibits phase locked Shapiro current spikes at voltages corresponding to integral multiples ofhω/2e, where ω = 2πf is the angular frequency of the rf field [9,20], and the height of the k-th order spike I k at voltage V k is proportional to the Bessel function of order k of the reduced ac voltage induced on the junction. When strong thermal fluctuations dominate the phase dynamics, and especially in our case where the typical frequency of phase-slip events f T ∼k B T n /h∼1.2 × 10 11 Hz is much greater than the frequency of the applied microwave field f = 1.5 × 10 10 Hz, phase locking cannot be achieved and the I − V characteristics will exhibit a broad peak instead of discrete spikes.…”

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confidence: 99%

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Fluctuation Dominated Josephson Tunneling with a Scanning Tunneling Microscope

2001

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We demonstrate Josephson tunneling in vacuum tunnel junctions formed between a superconducting scanning tunneling microscope tip and a Pb film, for junction resistances in the range 50-300 kΩ. We show that the superconducting phase dynamics is dominated by thermal fluctuations, and that the Josephson current appears as a peak centered at small finite voltage. In the presence of microwave fields (f = 15.0 GHz) the peak decreases in magnitude and shifts to higher voltages with increasing rf power, in agreement with theory. 07.79. Cz, 74.40.+k, 74.50.+r Scanning tunneling microscopy (STM) has been extensively used in the study of high-T c superconductors (HTSC), providing a spectroscopic tool with unparalleled energy and spatial resolution. Yet, while superconducting tips have been demonstrated in the past [1] all STM studies so far have been performed using normal-metal tips, thus probing only the single-particle excitation spectrum, the gap structure which is a consequence of superconductivity, but not the superconducting (SC) ground state itself. Results from STM measurements of HTSC show excitation gaps in situations where superconductivity is believed to be absent (pseudo-gap), such as in vortex cores [2] and above T c in underdoped samples [3], as well as inhomogenieties in the gap structure in reportedly high quality BiSrCaCuO crystals [4]. These results, due to the nature of the measurements, do not remove the ambiguity with respect to the existence of a finite SC pair amplitude in the situations studied.

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“…At an experimental temperature of 0.3 K, for aluminum having a bandgap of 170 μeV, the decay time should be τ rec ∼ 30 μs. 2,21,22 Both longitudinal and transverse phonon modes are expected to emerge from each process. 2 The excited phonon spectrum is thus highly non-thermal, comprising a nearly monochromatic component of recombination phonons of energy ∼2 , plus a broad distribution of relaxation phonons with a sharp cutoff at eV − 2 .…”

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confidence: 99%

Non-equilibrium phonon generation and detection in microstructure devices

Hertzberg

Otelaja

Yoshida

et al. 2011

Review of Scientific Instruments

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We demonstrate a method to excite locally a controllable, non-thermal distribution of acoustic phonon modes ranging from 0 to ∼200 GHz in a silicon microstructure, by decay of excited quasiparticle states in an attached superconducting tunnel junction (STJ). The phonons transiting the structure ballistically are detected by a second STJ, allowing comparison of direct with indirect transport pathways. This method may be applied to study how different phonon modes contribute to the thermal conductivity of nanostructures.

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Superconductive Tunnelling and Applications

Cited by 113 publications

References 0 publications

Response of thin-film SQUIDs to applied fields and vortex fields: Linear SQUIDs

Response of thin-film SQUIDs to applied fields and vortex fields: Linear SQUIDs

Fluctuation Dominated Josephson Tunneling with a Scanning Tunneling Microscope

Non-equilibrium phonon generation and detection in microstructure devices

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