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Andreev reflection between a normal metal and a superconductor whose order parameter exhibits quantum phase fluctuations is examined. The approach chosen is non perturbative in the tunneling Hamiltonian and enables to probe the whole range…

Superconductivity · Physics 2009-11-07 P. Devillard , R. Guyon , T. Martin , I. Safi , B. K. Chakraverty

Here we review the literature concerning measurement of the Andreev reflection between a superconductor (S) and ferromagnet (F), with particular attention to the case where the ferromagnet is a transition metal oxide. We discuss the…

Materials Science · Physics 2015-03-03 Karen A Yates , Lesley F Cohen

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

We study tunneling in ferromagnet/unconventional superconductor (F/S) junctions. We include the effects of spin polarization, interfacial resistance, and Fermi wavevector mismatch (FWM) between the F and S regions. Andreev reflection (AR)…

Superconductivity · Physics 2009-10-31 Igor Zutic , Oriol T. Valls

A theory of spin polarized tunneling spectroscopy based on a scattering theory is given for tunneling junctions between ferromagnets and d-wave superconductors. The spin filtering effect of an exchange field in the insulator is also…

Superconductivity · Physics 2009-10-31 S. Kashiwaya , Y. Tanaka , N. Yoshida , M. R. Beasley

Despite extensive search for about a decade, specular Andreev reflection is only recently realized in bilayer graphene-superconductor interface. However, the evolution from the typical retro type Andreev reflection to the unique specular…

Mesoscale and Nanoscale Physics · Physics 2017-01-04 Manas Ranjan Sahu , Pratap Raychaudhuri , Anindya Das

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 transport properties of a hybrid nanostructure composed of a ferromagnet, two quantum dots, and a superconductor connected in series. By using the non-equilibrium Green's function approach, we have calculated the electric…

Mesoscale and Nanoscale Physics · Physics 2015-05-14 E. C. Siqueira , G. G. Cabrera

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

We review application of point-contact Andreev-reflection spectroscopy to study elemental superconductors, where theoretical conditions for the smallness of the point-contact size with respect to the characteristic lengths in the…

Superconductivity · Physics 2018-06-13 Yu. G. Naidyuk , K. Gloos

Hybrid superconductor/graphene (SC/g) junctions are excellent candidates for investigating correlations between Cooper pairs and quantum Hall (QH) edge modes. Experimental studies are challenging as Andreev reflections are extremely…

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 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 review here a novel circuit theory of superconductivity. The existed circuit theory of Andreev reflection has been revised to account for decoherence between electrons and holes and twofold nature of the distribution function. The…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 Yuli V. Nazarov

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 report on transport measurements on Nb/Al/Gd/Al/Nb junctions.Bulk Gadolinium is a weakly polarized ferromagnet (5-7%), and is present in the junction in granular form (superparamagnet). We show that Andreev reflection is strongly…

Superconductivity · Physics 2007-05-23 O. Bourgeois , P. Gandit , J. Lesueur , R. Mélin , A. Sulpice , X. Grison , J. Chaussy

We study Andreev reflection in a ballistic one-dimensional channel coupled in parallel to a superconductor via a tunnel barrier of finite length $L$. The dependence of the low-energy Andreev reflection probability $R_A$ on $L$ reveals the…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Giorgos Fagas , Grigory Tkachov , Andreas Pfund , Klaus Richter

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

We present a description of spin-polarized transport in mesoscopic ferromagnet-superconductor (F/S) systems, where the transport is diffusive, and the interfaces are transparent. It is shown that the spin reversal associated with Andreev…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 F. J. Jedema , B. J. van Wees , B. H. Hoving , A. T. Filip , T. M. Klapwijk

In a point contact NS junction, perfect Andreev reflection occurs over a range of voltages equal to the superconducting energy gap, producing an excess current of $I_{exc} = (4/3)(2e\Delta/h)$. If the superconductor has a finite width,…

Superconductivity · Physics 2009-10-31 Richard Riedel , Philip F. Bagwell
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