Z. Pribulová

Specific heat measurements of a superconducting NbS2 single crystal in an external magnetic field: Energy gap structure

The heat capacity of a 2H-NbS2 single crystal has been measured by a highly sensitive ac technique down to 0.6 K and in magnetic fields up to 14 T. At very low temperatures, data show excitations over an energy gap (2ΔS/kBTc≈2.1) much smaller than the BCS value. The overall temperature dependence of the electronic specific heat Ce can be explained either by the existence of a strongly anisotropic single-energy gap or within a two-gap scenario with the large gap about twice bigger than the small one. The field dependence of the Sommerfeld coefficient γ shows a strong curvature for both principal-field orientations, parallel (H∥c) and perpendicular (H⊥c) to the c axis of the crystal, resulting in a magnetic field dependence of the superconducting anisotropy. These features are discussed in comparison to the case of MgB2 and to the data obtained by scanning-tunneling spectroscopy. We conclude that the two-gap scenario better describes the gap structure of NbS2 than the anisotropic s -wave model.

Single-gap superconductivity in β − B i 2 Pd

This work was supported by the Slovak projects APVV-0036-11, APVV-14-0605, VEGA 2/0149/16, VEGA 1/0409/15, by the ERDF EU grant under contract No. ITMS26220120005 and the COST action MP1201 as well as by the U.S. Steel Kosice. Sample growth was partially supported by the projects No. FIS2014-54498-R (MINECO, Spain) and No. S2013/MIT-2850 Nanofrontmag-CM (Region of Madrid, Spain) and by the Engineering and Physical Sciences Research Council, UK. E.H. acknowledges support from the Grant No. 560-2012 programa de doctorados en el exterior (COLCIENCIAS)

Superconducting energy gap in MgCNi3 single crystals: Point-contact spectroscopy and specific-heat measurements

Specific heat has been measured down to 600 mK and up to 8 T by highly sensitive ac microcalorimetry on MgCNi3 single crystals with Tc ≈ 7 K. Exponential decay of the electronic specific heat at low temperatures proved that a superconducting energy gap is fully open on the whole Fermi surface, in agreement with our previous magnetic penetration depth measurements on the same crystals. The specific-heat data analysis shows consistently the strong-coupling strength 2 /kBTc ≈ 4. This scenario is supported by the direct measurements of the gap via the point-contact spectroscopy. Moreover, the spectroscopy measurements show a decrease in the critical temperature at the sample surface, which accounts for the observed differences of the superfluid density deduced from the measurements by different techniques.

Magnetic and thermodynamic properties of CuxTiSe2 single crystals

We present a detailed study of the phase diagram of copper intercalated TiSe

Point-Contact Spectroscopy of Multigap Superconductors

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Possible two-gap superconductivity in NdFeAsO0.9F0.1 probed by point-contact Andreev-reflection spectroscopy

single crystals, combining local Hall-probe magnetometry, tunnel diode oscillator technique (TDO), specific-heat, and angle-resolved photoemission spectroscopy measurements. A series of the Cu

Point-contact spectroscopy of the phononic mechanism of superconductivity in YB6

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Two-Gap Superconductivity in 2H-NbS2

TiSe

Superconducting energy gap in MgCNi3 single crystals

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Type II superconductivity in SrPd2Ge2

samples from three different sources with various copper content