Normal reflection effect on the critical current in a clean-limit superconductor-normal-metal-superconductor junction

Tang, Han-Zhao; Wang, Z.D.; Zhang, Yuheng

doi:10.1007/s002570050220

Cited by 17 publications

(15 citation statements)

References 12 publications

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“…The values of these coefficients depend on the material details of the junction. The CPRs of junctions with FWVM 46 and barriers 37,50,51 have been previously calculated (numerically) at zero magnetic field. The effect of both mechanisms is to make the CPR more closely resemble a sinusoidal curve.…”

Section: Discussionmentioning

confidence: 99%

“…In the general case, where FWVM and barriers are included at the S-N interfaces, the bound state energies and the continuum current must be calculated from the transmission matrix formalism 46 , in which the transmission matrix includes a normal (specular) reflection coefficient as well as an Andreev (retro) reflection coefficient. The values of these coefficients depend on the material details of the junction.…”

Section: Discussionmentioning

confidence: 99%

“…The imaginary component of energy results in a finite lifetime for the continuum level, reducing its contribution to the junction current, but for a long junction L > ∼ ξ 0 n,l , this contribution is significant, and cannot be ignored 37 . The continuum current due to the subband (n, l), J n,l (χ), is calculated using the transmission formalism 37,42,46 . We calculate the transmission coefficients for the electrical currents carried by electron-like and hole-like excitations incident on the S-N interfaces, resulting in leaky solutions in the N -section.…”

Section: E Bound State and Continuum Currentsmentioning

confidence: 99%

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Orbital Josephson interference in a nanowire proximity-effect junction

Gharavi

Baugh

2015

Phys. Rev. B

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A semiconductor nanowire based superconductor-normal-superconductor (SN S) junction is modeled theoretically. A magnetic field is applied along the nanowire axis, parallel to the current. The Bogoliubov-de Gennes equations for Andreev bound states are solved while considering the electronic subbands due to radial confinement in the N -section. The energy-versus-phase curves of the Andreev bound states shift in phase as the N -section quasiparticles with orbital angular momentum couple to the axial field. A similar phase shift is observed in the continuum current of the junction. The quantum mechanical result is shown to reduce to an intuitive, semi-classical model when the Andreev approximation holds. Numerical calculations of the critical current versus axial field reveal flux-aperiodic oscillations that we identify as a novel form of Josephson interference due to this orbital subband effect. This behavior is studied as a function of junction length and chemical potential. Finally, we discuss extensions to the model that may be useful for describing realistic devices.The Josephson effect is characterized by a currentphase relationship (CPR) linking macroscopic current flow to the phase gradient of the superconducting order parameter1 . The precise form of the CPR for a superconducting weak link depends on intrinsic factors such as junction geometry, material properties, coherence lengths, etc., in addition to extrinsic variables like temperature and magnetic field. In superconductor-normalsuperconductor (SN S) junctions in which the N -section is long enough to suppress direct tunnelling of Cooper pairs, but shorter than the N -section phase coherence length, a supercurrent may be carried by quasiparticles undergoing Andreev reflection at the S-N interfaces 2-5 . Planar SN S junctions of width large compared to the S-section superconducting coherence length have been studied in great detail 6 (width refers to the dimension perpendicular to the current). These have revealed, for example, Fraunhofer oscillations of the critical current I c with respect to an externally applied out-of-plane magnetic field 7-9 . For junction widths comparable to the S-section coherence length, i.e. the narrow junction limit, this becomes a quasi-Gaussian, monotonic decay of the critical current 7,10,11 . Recently, attention has been given to nanoscale, quasi one-dimensional (1D) SN S junctions, such as those readily engineered by contacting semiconductor nanowires with superconducting leads [12][13][14][15][16] . Gating the semiconducting N -section allows for modulating the supercurrent by controlling the chemical potential 12,15 . The oscillations of the magnetoresistance of a nanowire SN S junction in the voltage-biased state (i.e. no dc supercurrent) versus an axial magnetic field have been studied 16 . Efforts to realize Majorana fermion quasiparticles in 1D semiconductors with strong spin-orbit interaction and proximity coupling to a superconductor 17-20 have further raised interest in this type of junction. Theoretical resul...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: E Bound State and Continuum Currentsmentioning

confidence: 99%

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Orbital Josephson interference in a nanowire proximity-effect junction

Gharavi

Baugh

2015

Phys. Rev. B

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“…This is because we impose a barrier potential at the SC/FM interfaces and include the Fermi velocity mismatch among different regions in numerical calculations, which remove all degeneracies in analytical results. The anti-crossing changes the period of the Josephson current at zero temperature, I s = 2e n ∂E n /∂φ with the sum-mation of negative Andreev levels, from 4π (black curves) to 2π [33,35]. The Josephson current for the Fig.…”

mentioning

confidence: 99%

Long-Range Spin-Triplet Helix in Proximity Induced Superconductivity in Spin-Orbit-Coupled Systems

2014

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We study proximity induced triplet superconductivity in a spin-orbit-coupled system, and show that the d vector of the induced triplet superconductivity undergoes precession that can be controlled by varying the relative strengths of Rashba and Dresselhaus spin-orbit couplings. In particular, a long-range spin-triplet helix is predicted when these two spin-orbit couplings have equal strengths. We also study the Josephson junction geometry and show that a transition between 0 and π junctions can be induced by controlling the spin-orbit coupling with a gate voltage. An experimental setup is proposed to verify these effects. Conversely, the observation of these effects can serve as a direct confirmation of triplet superconductivity.

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“…14 The Josephson effect in ballistic superconductor/normal conductor/superconductor junctions can be described within the framework of phase-coherent Andreev reflection. [15][16][17][18] In the Andreev reflection process an electron incident from the normal conductor side on the normal conductor/ superconductor interface is retroreflected as a hole by creating a Cooper pair in the superconductor. 19 In the reverse process, a hole is retroreflected as an electron by annihilating a Cooper pair in the superconductor.…”

Section: Introductionmentioning

confidence: 99%

Current-injection in a ballistic multiterminal superconductor/two-dimensional electron gas Josephson junction

et al. 2003

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We study the suppression of the critical current in a multi-terminal superconductor/two-dimensional electron gas/superconductor Josephson junction by means of hot carrier injection. As a superconductor Nb is used, while the two-dimensional electron gas is located in a strained InGaAs/InP heterostructure. Two different modes of injection are employed. First, in the three-terminal injection mode, where the injection current flows from an injector contact to one of the superconducting electrodes, only a partial suppression is obtained. Second, in the four-terminal mode, where the injection current flows between two opposite injector contacts, a complete suppression is achieved. A theoretical model for the critical current suppression in a short junction is presented, which takes the two-dimensional character of the junction into account. Qualitatively, the experimental data agree well with the theoretical predictions. The injection voltage required in the experiment to suppress the supercurrent is lower than theoretically predicted. This is explained by the fact that the width of the normal region of the junction is slightly too large to be in the short-junction limit.

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Normal reflection effect on the critical current in a clean-limit superconductor-normal-metal-superconductor junction

Cited by 17 publications

References 12 publications

Orbital Josephson interference in a nanowire proximity-effect junction

Orbital Josephson interference in a nanowire proximity-effect junction

Long-Range Spin-Triplet Helix in Proximity Induced Superconductivity in Spin-Orbit-Coupled Systems

Current-injection in a ballistic multiterminal superconductor/two-dimensional electron gas Josephson junction

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