Antonio Jefferson S. Machado

Superconductivity in non-centrosymmetric ThCoC2

Superconductivity in compounds whose crystal structure lacks inversion symmetry are known to display intriguing properties that deviate from conventional BCS superconducting behavior. Here we report magnetization, resistivity, and heat capacity measurements on polycrystalline samples of ThCoC2, which has been reported to crystallize in the non-centrosymmetric CeNiC2 prototype structure, and show clear evidence of bulk superconductivity in ThCoC2 with a critical temperature of Tc = 2.65?K. From the specific heat data we find a Sommerfeld coefficient of ? = 8.38?mJ?mol?1?K?2 and a Debye temperature of ?D = 449?K. Interestingly the Hc2 superconducting phase diagram displays positive curvature, and the specific heat at low temperature deviates from conventional exponential temperature dependence, which is suggestive of possible unconventional superconducting behavior in ThCoC2, similar to that seen in the isostructural and isoelectronic non-centrosymmetric superconductor LaNiC2.

Transport Properties of Granular High-TC Superconductors

We report on the application of the Resistively Shunted Junction (RSJ) model to granular high TC superconductors. Some derived predictions of the RSJ model are applied to a set of superconducting granular samples which can be considered as a network of Josephson junctions. The investigated samples belong to both holedoped Y1ixPrxBa2Cu3O7id (x = 0.0, 0.35, and 0.45) and the electron-doped Sm2ixCexCuO4id (x = 0:18) systems which display the so-called double resistive superconducting transition. We have performed several transport measurements in these compounds including temperature and magnetic field dependence of the electrical resistance, R(T; H), and I-V characteristics. Several aspects of the I-V characteristics were quantitatively well described by the RSJ model. The combined results strongly suggest that dissipation in granular superconducting samples is a natural consequence of the normal current flowing in parallel with the supercurrent current.

Conventional superconductivity properties of the ternary boron-nitride Nb2BN

The superconducting bulk properties of ternary Nb2BN are confirmed and described by means of magnetization, electronic transport and specific heat measurements. BCS conventional superconductivity is found with Tc = 4.4 K. Critical fields of Hc1(0) = 93 Oe and Hc2(0) = 2082 Oe are extrapolated by magnetic and resistivity measurements. The specific heat data reveal γ = 6.3 mJ mol−1 K−2 and β = 0.293 mJ mol−1 K−4, in good agreement with the BCS theory.

Properties and superconductivity in Ti-doped NiTe2 single crystals

Abstract Transition metal dichalcogenides (TMDs) usually show simple structures, however, with interesting properties. Recently some TMDs have been pointed out as type-II Dirac semimetals. In the present work, we investigate the physical properties of a new candidate for type-II Dirac semimetal and investigate the effect of titanium doping on physical properties of Ti-doped single crystalline samples of NiTe2. It was found that this compound shows superconducting properties with a critical temperature close to 4.0u202fK. Interestingly, applied pressures up to 1.3u202fGPa have no effect upon the superconducting state. Density Functional Theory (DFT) calculations demonstrate the presence of a Dirac cone in the band structure of NiTe2 literature when Spin-Orbit Coupling (SOC) is included, which is in agreement with a recent report for this compound. Also, our calculations demonstrate that Ti suppresses the formation of these non-trivial states.