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We report a systematic investigation on c-axis point-contact Andreev reflection (PCAR) in BaFe$_{2-x}$Ni$_x$As$_2$ superconducting single crystals from underdoped to overdoped regions (0.075 $\leq x\leq 0.15$). At optimal doping ($x=0.1$)…

The superconducting energy gap and quasiparticle density of states (DOS) is measured by means of Andreev-reflection spectroscopy in normal metal - superconductor point contacts. It is found that both in paramagnetic and in…

Superconductivity · Physics 2007-05-23 I. K. Yanson

Point-contact Andreev reflection spectroscopy at low temperatures and high magnetic fields has been performed on a noncentrosymmetric La$_3$Se$_4$ superconductor with a critical temperature $T_c$ = 8 K. Two superconducting energy gaps…

We have analyzed about 100 voltage-dependent differential resistance dV/dI(V) curves of metallic point contacts between c-axis oriented MgB$_2$ thin film and Ag, which exhibit clear Andreev reflection features connected with the…

A deep understanding of the character of superconductivity in the recently discovered Fe-based oxypnictides ReFeAsO1-xFx (Re = rare-earth) necessarily requires the determination of the number of the gaps and their symmetry in k space, which…

We report the results of the first directional point-contact measurements in Mg(B_{1-x}C_{x})_2 single crystals with 0.047 <= x <= 0.132. The two-gap superconductivity typical of MgB_2 persists up to x=0.105. In this region, the values of…

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 the results of directional point-contact measurements in MgB_2 single crystals, in magnetic fields up to 9 T parallel to the c axis. By fitting the conductance curves of our point contacts -- showing clear Andreev-reflection…

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

The results of Point Contact Andreev Reflection Spectroscopy on polycrystalline RuSr$_2$GdCu$_2$O$_8$ pellets are presented. The wide variety of the measured spectra are all explained in terms of a modified BTK model considering a…

Coherent charge transport along ballistic paths can be introduced into graphene by Andreev reflection, for which an electron reflects from a superconducting contact as a hole, while a Cooper pair is transmitted. We use a liquid-helium…

Mesoscale and Nanoscale Physics · Physics 2020-08-26 S. Bhandari , G. -H. Lee , K. Watanabe , T. Taniguchi , P. Kim , R. M. Westervelt

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

Point-contact Andreev reflection measurements of Co/ and Cu/tungsten-carbide (WC$_x$) contacts are presented. Metallic thin films were patterned by e-beam-lithography and lift-off; tungsten carbide superconducting tips were grown directly…

Superconductivity · Physics 2009-12-08 J. Barzola-Quiquia , M. Ziese , P. Esquinazi , N. Garcia

Andreev reflection spectra have been measured in a new superconductor EuAsFeO0.85F0.15 having an unexpectedly low superconducting transition temperature Tc~11.3 K among related FeAs compounds on a base Sm and Gd surrounding Eu in the series…

We report the study of ballistic transport in normal metal/graphene/superconductor junctions in edge-contact geometry. While in the normal state, we have observed Fabry-P\'{e}rot resonances suggesting that charge carriers travel…

Mesoscale and Nanoscale Physics · Physics 2019-10-30 P. Pandey , R. Kraft , R. Krupke , D. Beckmann , R. Danneau

Point-contact Andreev reflection spectroscopy was performed on single crystals of the heavy-fermion superconductor PrOs$_{4}$Sb$_{12}$, down to 90mK and up to 3Tesla. The conductance spectra showed multiple structures, including zero-bias…

Superconductivity · Physics 2011-10-25 C. S. Turel , W. M. Yuhasz , R. Baumbach , M. B. Maple , J. Y. T. Wei

We present new Au/La_{2-x}Sr_{x}CuO_{4} (LSCO) point-contact conductance measures as a function of voltage and temperature in samples with 0.08 <= x <= 0.2. Andreev reflection features disappear at about the bulk Tc, giving no evidence of…

Superconductivity · Physics 2009-11-07 R. S. Gonnelli , A. Calzolari , D. Daghero , L. Natale , G. A. Ummarino , V. A Stepanov , M. Ferretti

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

The current-voltage characteristic (CVC) of break junction made from polycrystalline Bi_{1.8}Pb_{0.3}Sr_{1.9}Ca_2Cu_3O_x is investigated. The experimental CVC has hysteretic feature that reflects a part of a curve with negative differential…

Superconductivity · Physics 2007-05-23 D. M. Gokhfeld , D. A. Balaev , K. A. Shaykhutdinov , S. I. Popkov , M. I. Petrov

The possibility to reconstruct the electron-phonon interaction (EPI) function was demonstrated for S-c-N and S-c-S point contacts using the superconducting inelastic contribution to the excess current caused by Andreev reflection processes.…

Superconductivity · Physics 2014-05-28 N. L. Bobrov , A. V. Khotkevich , G. V. Kamarchuk , P. N. Chubov