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Andreev reflection-where an electron in a normal metal backscatters off a superconductor into a hole-forms the basis of low energy transport through superconducting junctions. Andreev reflection in confined regions gives rise to discrete…

AuBe is a chiral, non-centrosymmetric superconductor with transition temperature $T_C$ $\simeq$ 3.25 K. The broken inversion symmetry in its crystal structure makes AuBe a possible candidate to host a mixed singlet-triplet pairing symmetry…

We measured the optical conductivity of superconducting single crystals of Ba$_{1-x}$K$_{x}$Fe$_{2}$As$_{2}$ with $x$ ranging from 0.40 (optimal doping, $T_c = 39$ K) down to 0.20 (underdoped, $T_c = 16$ K), where a magnetic order coexists…

Superconductivity · Physics 2017-09-19 B. Xu , Y. M. Dai , H. Xiao , B. Shen , H. H. Wen , X. G. Qiu , R. P. S. M. Lobo

We use angle-resolved photoemission spectroscopy (ARPES) to investigate the properties of the energy gap(s) in optimally doped (Bi,Pb)2(Sr,La)2CuO6+d (Bi2201). We find that the spectral gap has two components in the superconducting state: a…

Superconductivity · Physics 2017-03-21 Takeshi Kondo , Tsunehiro Takeuchi , Adam Kaminski , Syunsuke Tsuda , Shik Shin

We theoretically demonstrate unusual features of superconducting proximity effect in gapped graphene which presents a pseudospin symmetry-broken ferromagnet with a net pseudomagnetization. We find that the presence of a band gap makes the…

Mesoscale and Nanoscale Physics · Physics 2015-06-11 Leyla Majidi , Malek Zareyan

We present in-plane infrared reflectance measurement on two superconducting cuprates with relatively low T$_c$: a nearly optimally-doped Bi$_2$Sr$_{1.6}$La$_{0.4}$CuO$_{6+\delta}$ with T$_c$=33 K and an underdoped…

Superconductivity · Physics 2013-11-20 T. Dong , F. Zhou , N. L. Wang

Superconducting tips of YBa$_{2} $Cu$_{3}$O$_{7-x}$ were used to perform point-contact Andreev reflection spectroscopy on half-metallic CrO$_{2}$ thin films. At 4.2K, strong suppression of the d-wave Andreev reflection characteristics was…

Superconductivity · Physics 2015-05-30 C. S. Turel , I. J. Guilaran , P. Xiong , J. Y. T. Wei

We investigate the electronic properties and the superconducting gap characteristics of a single crystal of hole-doped 122 Fe-pnictide Ba$_{0.65}$Na$_{0.35}$Fe$_2$As$_2$ by means of specific heat measurements. The specific heat exhibits a…

Superconductivity · Physics 2011-08-29 A. K. Pramanik , M. Abdel-Hafiez , S. Aswartham , A. U. B. Wolter , S. Wurmehl , V. Kataev , B. Büchner

Sub-gap conductance at a large area junction with a rough interface of a ferromagnet and a high-T$_{C}$ superconductor is superimposed by multiple peaks which is not expected from an ideal point contact Andreev reflection process. We…

Superconductivity · Physics 2009-03-25 N. Ghosh , H. Schmidt , M. Grundmann

We present point-contact (PC) Andreev-reflection measurements of a superconducting epitaxial c-axis oriented nickel borocarbide film LuNi2B2C (Tc=15.9 K). The averaged value of the superconducting gap is found to be 2.6 +/-0.2 meV in the…

Superconductivity · Physics 2010-10-01 O. E. Kvitnitskaya , Yu. G. Naidyuk , I. K. Yanson , T. Niemeier , G. Fuchs , B. Holzapfel , L. Schultz

We report the complex dielectric function of high-quality nearly-stoichiometric Rb2Fe4Se5 (RFS) single crystals with Tc=32 K determined by wide-band spectroscopic ellipsometry and time-domain transmission spectroscopy in the spectral range…

The thermal conductivity of organic superconductor kappa-(BEDT-TTF)2Cu(NCS)2 (Tc =10.4 K) has been studied in a magnetic field rotating within the 2D superconducting planes with high alignment precision. At low temperatures (T < 0.5 K), a…

Superconductivity · Physics 2009-11-07 Koichi Izawa , Hidemasa Yamaguchi , Takahiko Sasaki , Yuji Matsuda

The recent discovery of superconductivity in iron-arsenic compounds below a transition temperature (Tc) as high as 55K ended the monopoly of copper oxides (cuprates) in the family of high-Tc superconductors. A critical issue in…

Scanning tunneling spectroscopy was performed on single crystals of superconducting 2H-NbSe2, at 300 mK and in a magnetic field, up to 5 T, applied parallel to the ab-plane. This novel field geometry allows the quasiparticle…

Superconductivity · Physics 2011-11-01 I. Fridman , C. Kloc , J. Y. T. Wei

To resolve the discrepancies of the superconducting order parameter in quasi-two-dimensional NbSe_2, comprehensive specific-heat measurements have been carried out. By analyzing both the zero-field and mixed-state data with magnetic fields…

Superconductivity · Physics 2009-11-13 C. L. Huang , J. -Y. Lin , Y. T. Chang , C. P. Sun , H. Y. Shen , C. C. Chou , H. Berger , T. K. Lee , H. D. Yang

We report new measurements on sup-gap energy structure originating from multiple Andreev reflections in mesoscopic SNS junctions. The junctions were fabricated in a planar geometry with high transparency superconducting contacts of Al…

The study of the anisotropic superconductor MgB2 using a combination of scanning tunneling microscopy and spectroscopy reveals two distinct energy gaps at Delta1=2.3 meV and Delta2=7.1 meV. Different spectral weights of the partial…

Superconductivity · Physics 2009-11-07 M. Iavarone , G. Karapetrov , A. E. Koshelev , W. K. Kwok , G. W. Crabtree , D. G. Hinks

The thermal conductivity of iron-based superconductor CsFe$_2$As$_2$ single crystal ($T_c =$ 1.81 K) was measured down to 50 mK. A significant residual linear term $\kappa_0/T$ = 1.27 mW K$^{-2}$ cm$^{-1}$ is observed in zero magnetic…

Superconductivity · Physics 2015-06-15 X. C. Hong , X. L. Li , B. Y. Pan , L. P. He , A. F. Wang , X. G. Luo , X. H. Chen , S. Y. Li

The differential resistances $R_d=dV/dI(V)$ of point contacts between a normal metal and a c axis oriented YNi2B2C film ($T_c$ = 15.2K) in the superconducting (SC) state have been investigated. $R_d(V)$ contains clear "gap" features…

Superconductivity · Physics 2009-11-11 D. L. Bashlakov , Yu. G. Naidyuk , I. K. Yanson , S. C. Wimbush , B. Holzapfel , G. Fuchs , S. -L. Drechsler

Iron-based compounds (IBS) display a surprising variety of superconducting properties that seems to arise from the strong sensitivity of these systems to tiny details of the lattice structure. In this respect, systems that become…