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We study diffusive magnetic Josephson junctions with four superconducting terminals in the weak proximity limit where the leads are arranged in cross form. Employing the linearized Keldysh-Usadel technique, the anomalous Green's function…

Superconductivity · Physics 2012-04-23 Mohammad Alidoust , Granville Sewell , Jacob Linder

Andreev reflection is investigated in layered anisotropic normal metal / superconductor (N/S) systems in the case of an energy gap \Delta in S not negligible with respect to the Fermi energy E_F, as it probably occurs with high critical…

Superconductivity · Physics 2009-10-31 A. A. Golubov , F. Tafuri

Starting from the quasiclassical equations for non-equilibrium Green's functions we derive a simple kinetic equation that governs ac Josephson effect in a superconducting quantum point contact at small bias voltages. In contrast to existing…

Condensed Matter · Physics 2009-10-28 D. Averin , A. Bardas

In this work we put forward an exact one-particle framework to study nano-scale Josephson junctions out of equilibrium and propose a propagation scheme to calculate the time-dependent current in response to an external applied bias. Using a…

Mesoscale and Nanoscale Physics · Physics 2015-05-14 Gianluca Stefanucci , Enrico Perfetto , Michele Cini

We apply the Keldysh formalism in order to derive a current formula easy to use for a system with many sites, one of which is interacting. The main technical challenge is to deal with the lesser Green function. It turns out that, in the…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 I. V. Dinu , M. Tolea , A. Aldea

We derive a formula for the current through an interacting quantum dot coupled to two supercouducting leads, using the non-equilibrium Green's function formalism. It is shown that the formula takes an especially simple form, when the…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 Kicheon Kang

We analyze the transport properties of contacts between unconventional superconductor and normal diffusive metal in the framework of the extended circuit theory. We obtain a general boundary condition for the Keldysh-Nambu Green's functions…

Superconductivity · Physics 2009-11-10 Y. Tanaka , Yu. V. Nazarov , A. A. Golubov , S. Kashiwaya

We theoretically analyze Josephson dynamics of superconducting weak links with transmissions ${\mathcal T}$ not much smaller than unity at subgap bias voltages $V$. Employing the effective action approach combined with the Keldysh technique…

Superconductivity · Physics 2023-06-27 Artem V. Galaktionov , Andrei D. Zaikin

We study electronic transport in junctions consisting of a superconductor electrode and two ferromagnet (F) leads in which crossed Andreev reflections (CAR) and elastic cotunnelings are accommodated. We model the system using an extended…

Superconductivity · Physics 2013-03-01 Kuei Sun , Nayana Shah , Smitha Vishveshwara

Particle transport across Josephson junctions is commonly described using a simplifying approximation (often called the Andreev approximation), which assumes that excitations are fixed at the Fermi momentum and only Andreev reflections,…

Mesoscale and Nanoscale Physics · Physics 2022-11-09 F. Setiawan , Johannes Hofmann

The time-dependent transport through a nano-scale device, consisting of a single spin-degenerate orbital with on-site Coulomb interaction, coupled to two leads, is investigated. Various gate and bias voltage time-dependences are considered.…

Mesoscale and Nanoscale Physics · Physics 2014-06-30 V. Vovchenko , D. Anchishkin , J. Azema , P. Lombardo , R. Hayn , A. -M. Daré

We study the electron transport through the quantum dot coupled to the normal metal and BCS-like superconductor (N - QD - S) in the presence of the Kondo effect and Andreev scattering. The system is described by the single impurity Anderson…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 M. Krawiec , K. I. Wysokinski

Employing quasiclassical theory of superconductivity combined with Keldysh technique we investigate large thermoelectric effect in multiterminal ballistic normal-superconducting (NS) hybrid structures. We argue that this effect is caused by…

Superconductivity · Physics 2017-02-01 Mikhail S. Kalenkov , Andrei D. Zaikin

Understanding the subgap behavior of Normal-Insulator-Superconductor (NIS) tunnel junctions is important in order to be able to accurately model the thermal properties of the junctions. Hekking and Nazarov developed a theory in which NIS…

Superconductivity · Physics 2011-11-23 Peter J. Lowell , Galen C. O'Neil , Jason M. Underwood , Joel N. Ullom

We present exact analytical results for the differential conductance of a finite Kitaev chain in an N-S-N configuration, where the topological superconductor is contacted on both sides with normal leads. Our results are obtained with the…

Mesoscale and Nanoscale Physics · Physics 2021-05-05 Nico Leumer , Magdalena Marganska , Bhaskaran Muralidharan , Milena Grifoni

We have investigated Andreev reflection at interfaces between superconducting indium (T_c = 3.4 K) and several normal conducting non-magnetic metals (palladium, platinum, and silver) down to T = 0.1 K as well as zinc (T_c = 0.87 K) in its…

Mesoscale and Nanoscale Physics · Physics 2015-06-12 Kurt Gloos , Elina Tuuli

We present a study of the Andreev reflections in superconductor/ferromagnet nanostructured point contacts. The experimental data are analyzed in the frame of a model with two spin-dependent transmission coefficients for the majority and…

Superconductivity · Physics 2009-11-10 F. Perez-Willard , J. C. Cuevas , C. Suergers , P. Pfundstein , J. Kopu , M. Eschrig , H. v. Loehneysen

A theory of crossed Andreev reflection in structures consisting of a superconductor with two ferromagnetic leads is presented. The electric current due to the crossed Andreev reflection strongly depends on the relative orientation of the…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 Taro Yamashita , Saburo Takahashi , Sadamichi Maekawa

A selfconsistent theory of the current-induced switching of magnetization using nonequilibrium Keldysh formalism is developed for a junction of two ferromagnets separated by a nonmagnetic spacer. It is shown that the spin-transfer torques…

Other Condensed Matter · Physics 2009-11-10 D. M. Edwards , F. Federici , J. Mathon , A. Umerski

We consider Andreev reflection in a two dimensional junction between a normal metal and a heavy fermion superconductor in the Fulde-Ferrell (FF) type of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state. We assume s-wave symmetry of the…

Superconductivity · Physics 2011-03-10 J. Kaczmarczyk , M. Sadzikowski , J. Spałek