Theory of thermal and charge transport in diffusive normal metal/superconductor junctions

Yokoyama, Takehito; Tanaka, Yukio; Golubov, Alexandre Avraamovitch; Asano, Yasuhiro

doi:10.1103/physrevb.72.214513

Cited by 32 publications

(43 citation statements)

References 90 publications

(146 reference statements)

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“…(19) of Ref. 31 Therefore, since the above treatment of the Eliashberg equation shows that the odd-frequency dependence of the gap may be taken into account simply by substituting ∆ → ∆(ε), quantum transport for an odd-frequency superconductor can be treated in the BTK-formalism by performing the same substitution. However, the derivation of the Bogolioubov-de Gennes equation for odd-frequency superconductivity is challenging since it is not obvious how to take into account the strong retardation effects of the pairing potential.…”

Section: A Equations For Odd-frequency Superconductivitymentioning

confidence: 99%

Quantum transport in a normal metal/odd-frequency superconductor junction

et al. 2008

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Recent experimental results indicate the possible realization of a bulk odd-frequency superconducting state in the compounds CeCu2Si2, and CeRhIn5. Motivated by this, we present a study of the quantum transport properties of a normal metal/odd-frequency superconductor junctions in a search for probes to unveil the oddfrequency symmetry. From the Eliashberg equations, we perform a quasiclassical approximation to account for the transport formalism of an odd-frequency superconductor with the Keldysh formalism. Specifically, we consider the tunneling charge conductance and tunneling thermal conductance. We find qualitatively distinct behaviour in the odd-frequency case as compared to the conventional even-frequency case, in both the electrical and thermal current. This serves as a useful tool to identify the possible existence of a bulk odd-frequency superconducting state.

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Section: A Equations For Odd-frequency Superconductivitymentioning

confidence: 99%

Quantum transport in a normal metal/odd-frequency superconductor junction

et al. 2008

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“…(6-9) one can compute the components f (x), f y (x) and f z (x) , and easily show that while f (x) and f z (x) decay into the ferromagnet over the magnetic length D/2h the long-ranged component f y (x) decays over the length given by D/2E. The charge and energy currents, I and Q respectively, can be obtained from 27,28,39,40 …”

Section: Model and Basic Equationsmentioning

confidence: 99%

Electron cooling in diffusive normal metal–superconductor tunnel junctions with a spin-valve ferromagnetic interlayer

et al. 2012

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We investigate heat and charge transport through a diffusive SIF 1 F 2 N tunnel junction, where N (S) is a normal (superconducting) electrode, I is an insulator layer and F 1,2 are two ferromagnets with arbitrary direction of magnetization. The flow of an electric current in such structures at subgap bias is accompanied by a heat transfer from the normal metal into the superconductor, which enables refrigeration of electrons in the normal metal. We demonstrate that the refrigeration efficiency depends on the strength of the ferromagnetic exchange field h and the angle α between the magnetizations of the two F layers. As expected, for values of h much larger than the superconducting order parameter ∆, the proximity effect is suppressed and the efficiency of refrigeration increases with respect to a NIS junction. However, for h ∼ ∆ the cooling power (i.e. the heat flow out of the normal metal reservoir) has a non-monotonic behavior as a function of h showing a minimum at h ≈ ∆. We also determine the dependence of the cooling power on the lengths of the ferromagnetic layers, the bias voltage, the temperature, the transmission of the tunneling barrier and the magnetization misalignment angle α.

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“…Without SO coupling, this typically occurs for exchange fields fulfilling the resonant condition 28,29 h ∼ E g , where E g is the minigap energy. However, the mechanism for the enhanced density of states due to triplets in the present work is fundamentally different from previous literature as it originates from a parity effect due to SO coupling which is present independently on the exact junction parameters.…”

Section: Theorymentioning

confidence: 99%

Giant triplet proximity effect inπ-biased Josephson junctions with spin-orbit coupling

Jacobsen

Linder

2015

Phys. Rev. B

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In diffusive Josephson junctions the phase-difference φ between the superconductors strongly influences the spectroscopic features of the layer separating them. The observation of a uniform minigap and its phase modulation were only recently experimentally reported, demonstrating agreement with theoretical predictions up to now -a vanishing minigap at φ = π. Remarkably, we find that in the presence of intrinsic spin-orbit coupling a giant proximity effect due to spin-triplet Cooper pairs can develop at φ = π, in complete contrast to the suppressed proximity effect without spin-orbit coupling. We here report a combined numerical and analytical study of this effect, proving its presence solely based on symmetry arguments, which makes it independent of the specific parameters used in experiments. We show that the spectroscopic signature of the triplets is present throughout the entire ferromagnetic layer. Our finding offers a new way to artificially create, control and isolate spin-triplet superconductivity.

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Theory of thermal and charge transport in diffusive normal metal/superconductor junctions

Cited by 32 publications

References 90 publications

Quantum transport in a normal metal/odd-frequency superconductor junction

Quantum transport in a normal metal/odd-frequency superconductor junction

Electron cooling in diffusive normal metal–superconductor tunnel junctions with a spin-valve ferromagnetic interlayer

Giant triplet proximity effect inπ-biased Josephson junctions with spin-orbit coupling

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