Influence of the impurity scattering on charge transport in unconventional superconductor junctions

Lu, Bo; Burset, Pablo; Tanuma, Y.; Golubov, A. A.; Asano, Yasuhiro; Tanaka, Yukio

doi:10.1103/physrevb.94.014504

Cited by 35 publications

(45 citation statements)

References 85 publications

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“…The resulting normalized tunnel conductance is strongly suppressed for small energies, featuring a (U-) V-shaped profile for (gapful) nodal pairing states. In the gapful trivial case the conductance tends to zero, while for the nodal trivial cases it tends to a finite but small value [15].…”

Section: Ballistic Junctionmentioning

confidence: 98%

“…The spatial dependence of the order parameter is determined self-consistently in terms of the quasiclassical Green's function, namely [15,36] …”

Section: Modelmentioning

confidence: 99%

“…[15], the self-energy for the distribution of nonmagnetic impurities is written asâ = 3 j =1 a jτj , with…”

Section: Modelmentioning

confidence: 99%

“…However, the height of the zero-bias peak and the gap suppression are very sensitive to the barrier strength and are also rounded by temperature effects [15]. Therefore, tunnel conductance experiments can sometimes be ambiguous.…”

Section: Ballistic Junctionmentioning

confidence: 99%

“…Some SABSs have a topological origin and would be protected against imperfections or impurities [9][10][11][12][13][14]. However, impurity scattering reduces or completely suppresses the ZBP for many cases, making it difficult to detect unconventional pairing symmetries from conductance measurements only [15]. To go beyond dc conductance, it is interesting to study the nonequilibrium current fluctuations or shot noise [16].…”

Section: Introductionmentioning

confidence: 99%

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Current fluctuations in unconventional superconductor junctions with impurity scattering

Burset

Tamura

et al. 2017

Phys. Rev. B

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The order parameter of bulk two-dimensional superconductors is classified as nodal if it vanishes for a direction in momentum space, or gapful if it does not. Each class can be topologically nontrivial if Andreev bound states are formed at the edges of the superconductor. Nonmagnetic impurities in the superconductor affect the formation of Andreev bound states and can drastically change the tunneling spectra for small voltages. Here, we investigate the mean current and its fluctuations for two-dimensional tunnel junctions between normal-metal and unconventional superconductors by solving the quasiclassical Eilenberger equation self-consistently, including the presence of nonmagnetic impurities in the superconductor. As the impurity strength increases, we find that superconductivity is suppressed for almost all order parameters since (i) at zero applied bias, the effective transferred charge calculated from the noise-current ratio tends to the electron charge e, and (ii) for finite bias, the current-voltage characteristics follows that of a normal-state junction. There are notable exceptions to this trend. First, gapful nontrivial (chiral) superconductors are very robust against impurity scattering due to the linear dispersion relation of their surface Andreev bound states. Second, for nodal nontrivial superconductors, only p x -wave pairing is almost immune to the presence of impurities due to the emergence of odd-frequency s-wave Cooper pairs near the interface. Due to their anisotropic dependence on the wave vector, impurity scattering is an effective pair-breaking mechanism for the remaining nodal superconductors. All these behaviors are neatly captured by the noise-current ratio, providing a useful guide to find experimental signatures for unconventional superconductivity.

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Section: Ballistic Junctionmentioning

confidence: 98%

“…The spatial dependence of the order parameter is determined self-consistently in terms of the quasiclassical Green's function, namely [15,36] …”

Section: Modelmentioning

confidence: 99%

“…[15], the self-energy for the distribution of nonmagnetic impurities is written asâ = 3 j =1 a jτj , with…”

Section: Modelmentioning

confidence: 99%

Section: Ballistic Junctionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Current fluctuations in unconventional superconductor junctions with impurity scattering

Burset

Tamura

et al. 2017

Phys. Rev. B

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P-wave Pairing Near a Spin-Split Josephson Junction

Seoane Souto,

Kuzmanovski,

Sardinero

et al. 2024

J Low Temp Phys

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Superconductivity and magnetism are competing effects that can coexist in certain regimes. Their co-existence leads to unexpected new behaviors that include the onset of exotic electron pair mechanisms and topological phases. In this work, we study the properties of a Josephson junction between two spin-split superconductors. The spin-splitting in the superconductors can arise from either the coupling to a ferromagnetic material or an external magnetic field. The properties of the junction are dominated by the Andreev bound states that are also split. One of these states can cross the superconductor’s Fermi level, leading to a ground-state transition characterized by a suppressed supercurrent. We interpret the supercurrent blockade as coming from a dominance of p-wave pairing close to the junction, where the electrons are at both sides. To support this interpretation, we analyze the different pairing channels and show that p-wave pairing is favored in the case where the magnetization of the two superconductors is parallel and suppressed in the anti-parallel case. We also analyze the noise spectrum that shows signatures of the ground-state transition in the form of an elevated zero-frequency noise.

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Electron waiting times in hybrid junctions with topological superconductors

Burset

Flindt

2018

Sci Rep

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We investigate the waiting time distributions (WTDs) of superconducting hybrid junctions, considering both conventional and topologically nontrivial superconductors hosting Majorana bound states at their edges. To this end, we employ a scattering matrix formalism that allows us to evaluate the waiting times between the transmissions and reflections of electrons or holes. Specifically, we analyze normal-metal–superconductor (NIS) junctions and NISIN junctions, where Cooper pairs are spatially split into different leads. The distribution of waiting times is sensitive to the simultaneous reflection of electrons and holes, which is enhanced by the zero-energy state in topological superconductors. For the NISIN junctions, the WTDs of trivial superconductors feature a sharp dependence on the applied voltage, while for topological ones they are mostly independent of it. This particular voltage dependence is again connected to the presence of topological edge states, showing that WTDs are a promising tool for identifying topological superconductivity.

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Influence of the impurity scattering on charge transport in unconventional superconductor junctions

Cited by 35 publications

References 85 publications

Current fluctuations in unconventional superconductor junctions with impurity scattering

Current fluctuations in unconventional superconductor junctions with impurity scattering

P-wave Pairing Near a Spin-Split Josephson Junction

Electron waiting times in hybrid junctions with topological superconductors

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