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We have studied the structure of the superconducting gap in MgB2 thin films by means of point-contact spectroscopy using a gold tip. The films were produced by depositing pure boron on a sapphire substrate, using e-beam evaporation,…

In this paper we highlight the advantages of using point-contact spectroscopy (PCS) in multigap superconductors like MgB_2, both as a fundamental research tool and as a non-destructive diagnostic technique for the optimization of thin-film…

The energy gap has been measured and the characteristic phonon energies determined for the superconducting compound $La_{1.8}Sr_{02}CuO_4$ from the current-voltage characteristics of point contacts with a copper counterelectrode. The…

We present the results of point-contact spectroscopy measurements in polycrystalline RuSr_2GdCu_2O_8 samples previously characterized from both the structural and the electrical point of view. AC susceptibility and resistivity measurements,…

Superconductivity · Physics 2007-05-23 G. A. Ummarino , A. Calzolari , D. Daghero , R. S. Gonnelli , V. A. Stepanov , R. Masini , M. R. Cimberle

High-impedance contacts made on the surface of Sr$_{0.88}$La$_{0.12}$CuO$_2$ superconducting thin films systematically display a zero-bias anomaly. We consider two-level systems (TLS) as the origin of this anomaly. We observe that the…

Superconductivity · Physics 2015-06-04 L. Fruchter , F. Bouquet , Z. Z. Li

The point-contact spectroscopy, in contrast to the tunneling spectrocopy, considers small electrical contacts with direct conductivity. In the normal state, it enables one to measure the spectral function of electron-boson interaction. In…

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

Point-contact spectroscopy is a powerful tool for probing superconductors. One of the most common observations in the point-contact spectra on the recently discovered ferropnictide superconductors is a large conductance asymmetry with…

Point-contact (PC) Andreev-reflection (AR) measurements of the superconducting gap in iron-oxipnictide ReFeAsO_{1-x}F_x (Re=La, Sm) films have been carried out. The value of the gap is distributed in the range 2\Delta \simeq 5-10 meV (for…

Superconductivity · Physics 2015-03-19 Yu. G. Naidyuk , O. E. Kvitnitskaya , I. K. Yanson , G. Fuchs , S. Haindl , M. Kidszun , L. Schultz , B. Holzapfel

The maximum value of the energy gap $\Delta\simeq 8\ meV$ and the ratio $2\delta/kT_c\simeq~2.5$ are determined for a high-temperature superconductor $\rm Bi_2Sr_2CaCu_2O_{8+y}$ by using point contacts. It was found that the…

Electrical characteristics $(I(eV), dV/dI(eV), d^{2}V/dI^{2}(eV))$ are studied comprehensively for pressed submicron point contacts between fresh fractures of LaSrCuO ceramic pellets and a normal metal (Cu). Point contacts (PC) with the…

We perform a point-contact Andreev reflection spectroscopic study of the topological superconducting material, Cu0.25Bi2Se3, in the ballistic regime using a normal-metal gold tip. We observe distinct point-contact spectra on the…

Superconductivity · Physics 2012-10-24 X. Chen , C. Huan , Y. S. Hor , C. A. R. Sá de Melo , Z. Jiang

The in-plane penetration depth of Sr$_{0.88}$La$_{0.12}$CuO$_{2+x}$ thin films at various doping obtained from oxygen reduction has been measured, using AC susceptibility measurements. For the higher doping samples, the superfluid density…

Superconductivity · Physics 2011-02-04 L. Fruchter , V. Jovanovic , H. Raffy , Sid Labdi , F. Bouquet , Z. Z. Li

In this letter we describe the observation of a magnetic field dependent electronic gap, suggestive of local superconductivity, in the point-contact spectrum of micro-crystalline graphite. Magnetic field dependent point-contact spectroscopy…

Superconductivity · Physics 2018-05-23 Frank Arnold , Jan Nyeki , John Saunders

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…

The superconducting order parameter and electron-phonon interaction (EPI) in a MgB$_{2}$ c-axis oriented thin film are investigated by point contacts (PCs). Two superconducting gaps $\Delta_{Small}\approx 2.6$ meV and $\Delta_{Large}\approx…

Lortz et al. [Phys. Rev. B 73, 024512 (2006)] have utilized specific heat and resistivity measurements as "thermal spectroscopies" to deconvolve the spectrum of the electron-phonon interaction in YB$_6$ assuming a major role of the low…

Superconductivity · Physics 2013-04-01 P. Szabo , J. Girovsky , Z. Pribulova , J. Kacmarcik , T. Mori , P. Samuely

The point-contact spectra of tetragonal $\rm YBa_2Cu_3O_{7-\delta}$ with $T_c=50-60~K$ are studied at various temperatures. The single-electron energy ($2\Delta_0/kT_c\simeq 17$) and its temperature dependence are determined. The…

Superconductivity · Physics 2017-02-03 I. K. Yanson , L. F. Rybal'chenko , V. V. Fisun , N. L. Bobrov , V. V. Demirskii , V. V. Mitkevich

A qualitative study of the electron-phonon interaction (EPI) spectra in $2H-NbS{{e}_{2}}$ is carried out by the method of point-contact spectroscopy in the superconducting state. Anisotropy of the EPI spectra for contacts oriented in the…

Superconductivity · Physics 2016-03-09 N. L. Bobrov , L. F. Rybal'chenko , M. A. Obolenskii , V. V. Fisun

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

Point contact spectroscopy (PCS) is a technique which can reveal the size and symmetry of a superconducting gap ($\Delta$) and is especially useful for new materials such as the iron-based superconductors. PCS is usually employed in…

Superconductivity · Physics 2012-11-21 John Timmerwilke , E. Kim , J. Maughan , J. S. Kim , G. R. Stewart , Amlan Biswas
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