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We study the Andreev and normal reflection processes -- retro as well as specular -- in a bilayer graphene-superconductor junction where equal and opposite displacement fields are applied for the top and bottom layers to induce a band gap.…

Superconductivity · Physics 2023-11-17 Panch Ram , Detlef Beckmann , Romain Danneau , Wolfgang Belzig

We investigate electron transport through the interface between a niobium superconductor and the edge of a two-dimensional semimetal, realized in a 20~nm wide HgTe quantum well. Experimentally, we observe that typical behavior of a single…

Mesoscale and Nanoscale Physics · Physics 2016-02-03 A. Kononov , S. V. Egorov , Z. D. Kvon , N. N. Mikhailov , S. A. Dvoretsky , E. V. Deviatov

We develop a new theoretical approach for modelling a wide range of semiconductor-superconductor structures with arbitrary potential barriers and a spatially-dependent superconducting order parameter. We demonstrate asymmetry in the…

Superconductivity · Physics 2018-03-14 Shlomi Bouscher , Roni Winik , Alex Hayat

We theoretically propose the laser-induced Andreev reflection between two-component Fermi superfluid and normal states via spatially-uniform Rabi couplings. By analyzing the tunneling current between the superfluid and normal states up to…

Quantum Gases · Physics 2023-05-01 Tingyu Zhang , Hiroyuki Tajima , Yuta Sekino , Shun Uchino , Haozhao Liang

We theoretically demonstrate that a ferromagnetic/superconductor junction on the surface of three-dimensional topological insulators (3D TIs) has an anisotropic angle-dependent Andreev reflection when the in-plane magnetization has a…

Superconductivity · Physics 2023-02-08 Morteza Salehi

Reflectionless-tunneling was observed in Nb/GaAs superconductor/semiconductor junctions fabricated through a two-step procedure. First, periodic $\delta$-doped layers were grown by molecular beam epitaxy near the GaAs surface, followed by…

The transport properties of a ferromagnet-superconductor (FS) junction are studied in a scattering formulation. Andreev reflection at the FS interface is strongly affected by the exchange interaction in the ferromagnet. The conductance G_FS…

Condensed Matter · Physics 2017-12-07 M. J. M. de Jong , C. W. J. Beenakker

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 report an experimental study of induced superconductivity in Ge hut nanowire Josephson junctions. The Ge hut nanowires are grown on prepatterned SiGe ridges via molecular beam epitaxy (MBE) and Josephson junction devices are fabricated…

Mesoscale and Nanoscale Physics · Physics 2026-01-23 Han Gao , Jian-Huan Wang , Ji-Yin Wang , Jian-Jun Zhang , Hongqi Xu

We made point-contact measurements with Au tips on La_{2-x}Sr_{x}CuO_{4} samples with 0.08 < x < 0.20 to investigate the relationship between superconducting gap and pseudogap. We obtained junctions whose conductance curves presented…

Superconductivity · Physics 2015-06-24 R. S. Gonnelli , A. Calzolari , D. Daghero , L. Natale , G. A. Ummarino , V. A. Stepanov , M. Ferretti

We demonstrate the transfer of the superconducting properties of NbTi---a large-gap high-critical-field superconductor---into an InAs heterostructure via a thin intermediate layer of epitaxial Al. Two device geometries, a Josephson junction…

Mesoscale and Nanoscale Physics · Physics 2017-02-14 A. C. C. Drachmann , H. J. Suominen , M. Kjaergaard , B. Shojaei , C. J. Palmstrøm , C. M. Marcus , F. Nichele

Our previous point-contact Andreev reflection studies of the heavy-fermion superconductor CeCoIn$_5$ using Au tips have shown two clear features: reduced Andreev signal and asymmetric background conductance [1]. To explore their physical…

In the "ballistic" regime, the transport across a normal metal (N)/superconductor (S) point-contact is dominated by a quantum process called Andreev reflection. Andreev reflection causes an enhancement of the conductance below the…

Superconductivity · Physics 2021-10-04 Ritesh Kumar , Goutam Sheet

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

Coherent transport in Nb/GaAs superconductor-semiconductor microstructures is presented. The structures fabrication procedure is based on delta-doped layers grown by molecular-beam-epitaxy near the GaAs surface, followed by an As cap layer…

Superconductivity · Physics 2009-11-10 F. Giazotto , P. Pingue , F. Beltram

Low temperature transport measurements on superconducting film - normal metal wire - superconducting film (SNS) junctions fabricated on the basis of 6 nm thick superconducting polycrystalline PtSi films are reported. The structures with the…

Andreev reflection spectroscopy has been performed on the heavy-fermion superconductor (HFS) CeCoIn$_5$ single crystals along three different crystallographic orientations, (001), (110), and (100), using Au tips as counter-electrodes.…

Superconductivity · Physics 2011-11-09 Wan Kyu Park , Laura H. Greene , John L. Sarrao , Joe D. Thompson

Measurement of multiple Andreev reflection (MAR) in a Josephson junction made from an InAs heterostructure with epitaxial aluminum is used to quantify the highly transparent semiconductor-superconductor interface, indicating near-unity…

Mesoscale and Nanoscale Physics · Physics 2017-03-31 M. Kjaergaard , H. J. Suominen , M. P. Nowak , A. R. Akhmerov , J. Shabani , C. J. Palmstrøm , F. Nichele , C. M. Marcus

We address the controversy over the proximity effect between topological materials and high T$_{c}$ superconductors. Junctions are produced between Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ and materials with different Fermi surfaces…

We experimentally investigate Andreev transport through the interface between an indium superconductor and the edge of the InAs/GaSb bilayer. To cover all possible regimes of InAs/GaSb spectrum, we study samples with 10 nm, 12 nm, and 14 nm…

Mesoscale and Nanoscale Physics · Physics 2017-12-20 A. Kononov , V. A. Kostarev , B. R. Semyagin , V. V. Preobrazhenskii , M. A. Putyato , E. A. Emelyanov , E. V. Deviatov