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We develop a quasiclassical theory of Andreev interferometers with three superconducting electrodes. Provided tunneling interface resistance between one superconducting electrode and the normal metal strongly exceeds two others, significant…

Superconductivity · Physics 2015-06-04 A. V. Galaktionov , A. D. Zaikin , L. S Kuzmin

We study the transport properties of nanoscale superconducting (S) devices in which two superconducting electrodes are bridged by two parallel ferromagnetic (F) wires, forming an SFFS junction with a separation between the two wires less…

Superconductivity · Physics 2012-06-05 Madalina Colci , Kuei Sun , Nayana Shah , Smitha Vishveshwara , Dale J. Van Harlingen

We study Multiple Andreev Reflections in long diffusive superconductor(S)-normal metal(N)-superconductor junctions with low-transparency interfaces. Assuming strong thermalization in the weak link we calculate the current-voltage dependence…

Superconductivity · Physics 2022-09-16 A. V. Polkin , P. A. Ioselevich

We calculate the conductance of a junction between a disordered superconductor and a very strong half-metallic ferromagnet admitting electrons with only one spin projection. A usual mechanism of Andreev reflection is strongly suppressed in…

Superconductivity · Physics 2024-01-29 M. E. Ismagambetov , P. M. Ostrovsky , M. V. Feigel'man

We present a theory of Andreev reflection in a ferromagnet/superconductor/ferromagnet double junction system. The spin polarized quasiparticles penetrate to the superconductor in the range of penetration depth from the interface by the…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Taro Yamashita , Hiroshi Imamura , Saburo Takahashi , Sadamichi Maekawa

The electron transport though ferromagnetic metal-superconducting hybrid devices is considered in the non-equilibrium Green's function formalism in the quasiclassical approximation. Attention if focused on the limit in which the exchange…

Superconductivity · Physics 2009-10-31 W. Belzig , Arne Brataas , Yu. V. Nazarov , Gerrit E. W. Bauer

We study the Andreev reflection (AR) in a three terminal mesoscopic hybrid system, in which two ferromagnets (F$_1$ and F$_2$) are coupled to a superconductor (S) through a quantum dot (QD). By using non-equilibrium Green function, we…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Yu Zhu , Qing-feng Sun , Tsung-han Lin

We show that spin-polarized electron transmission across semiconductor/superconductor (Sm/S) hybrid structures depends sensitively on the degree of spin polarization as well as the strengths of potential and spin-flip scattering at the…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 Igor Zutic , S. Das Sarma

We present here an extensive theoretical analysis of the supercurrent of a superconducting point contact of arbitrary transparency in the presence of a microwave field. Our study is mainly based on two different approaches: a two-level…

Superconductivity · Physics 2015-05-28 F. S. Bergeret , P. Virtanen , A. Ozaeta , T. T. Heikkilä , J. C. Cuevas

Motivated by the recent experiment of Wang et al. [Nature Physics 6, 389 (2010)], who observed a highly unusual transport behavior of ferromagnetic Cobalt nanowires proximity-coupled to superconducting electrodes, we study proximity effect…

Superconductivity · Physics 2015-06-03 So Takei , Victor Galitski

We show that Andreev reflection in a junction between ferromagnetic (F) and superconducting (S) graphene regions is fundamentally different from the common FS junctions. For a weakly doped F graphene with an exchange field $h$ larger than…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 Malek Zareyan , Hakimeh Mohammadpour , Ali G. Moghaddam

We discuss very low temperature experiments on superconducting micro-coolers made of a double Normal metal - Insulator - Superconductor junction. We investigate with a high resolution the differential conductance of the micro-cooler as well…

Superconductivity · Physics 2009-11-13 Sukumar Rajauria , Philippe Gandit , F. W. J. Hekking , Bernard Pannetier , Hervé Courtois

We propose that, if the pseudogap state in the cuprate superconductors can be described in terms of the phase-incoherent preformed pairs, there should exist Andreev reflection from these pairs even above the superconducting transition…

Superconductivity · Physics 2009-10-31 Han-Yong Choi , Yunkyu Bang , David K. Campbell

We have measured the tunnelling current in Nb/Nb$_x$O$_y$/Ni planar tunnel junctions at different temperatures. The junctions are in the intermediate transparency regime. We have extracted the current polarization of the metal/ferromagnet…

Superconductivity · Physics 2009-11-13 E. M. González , A. D. Folgueras , R. Escudero , J. Ferrer , F. Guinea , J. L. Vicent

We consider the conductance of an Andreev interferometer, i.e., a hybrid structure where a dissipative current flows through a mesoscopic normal (N) sample in contact with two superconducting (S) "mirrors". Giant conductance oscillations…

Condensed Matter · Physics 2009-10-30 H. A. Blom , A. Kadigrobov , A. M. Zagoskin , R. I. Shekhter , M. Jonson

The Andreev reflection of narrow ferromagnet/superconductor point contacts is theoretically studied. We show that the conductance quantization depends on whether the contact region is superconducting or ferromagnetic as well as on the…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Keiichirou Kikuchi , Hiroshi Imamura , Saburo Takahashi , Sadamichi Maekawa

We investigate conductances and current correlations in a system consisting of a normal multichannel conductor connected to one superconducting and two ferromagnetic electrodes. For antiparallel orientation of the ferromagnet polarizations,…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 David Sanchez , Rosa Lopez , Peter Samuelsson , Markus Buttiker

The behavior of dc subgap current in magnetic quantum point contact is discussed for the case of low-transparency junction with different tunnel probabilities for spin-up ($D_\uparrow$) and spin-down ($D_\downarrow$) electrons. Due to the…

Superconductivity · Physics 2009-11-11 I. V. Bobkova

Ag/BSCCO and Fe/Ag/BSCCO planar tunnel junctions were constructed in order to study experimentally the effect of an exchange potential on the spin polarized current transported through Andreev bound states appearing at the interface with a…

Superconductivity · Physics 2007-05-23 Mario Freamat , K. -W. Ng

We study the Josephson effect in a clean Superconductor-Ferromagnet-Superconductor junction for arbitrarily large spin polarizations. The Andreev reflection at a clean Ferromagnet-Superconductor interface is incomplete, and Andreev channels…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 J. Cayssol , G. Montambaux