Possible multiband superconductivity in the quaternary carbide YRe₂SiC

Abstract

We report for the first time the occurrence of superconductivity in the quaternary silicide carbide YRe2SiC with Tc ≈ 5.9 K. The emergence of superconductivity was confirmed by means of magnetic susceptibility, electrical resistivity, and heat capacity measurements. The presence of a well developed heat capacity feature at Tc confirms that superconductivity is a bulk phenomenon, while a second feature in the heat capacity near 0.5 Tc combined with the unusual temperature dependence of the upper critical field Hc2(T) indicate the presence of a multiband superconducting state. Additionally, the linear dependence of the lower critical field Hc1 with temperature resemble the behavior found in compounds with unconventional pairing symmetry. Band structure calculations reveal YRe2SiC could harbor a non-trivial topological state and that the low-energy states occupy multiple disconnected sheets at the Fermi surface, with different degrees of hybridization, nesting, and screening effects, therefore making unconventional multiband superconductivity plausible.

Superconductivity in Te-Deficient ZrTe2

“…The H c 2 ( T ) data show an upturn below T c , in sharp contrast with the expected quadratic behavior of single-band superconductivity and the Werthamer–Helfand–Hohenberg (WHH) single-gap model . The positive curvature of H c 2 below T c is frequently taken as an indication of multiband SC. − Alternatively, the fit of the H c 2 ( T ) data to the two-band model proposed by Gurevich results in an excellent fit, as seen in Figure , where it is represented by the dashed black line. In Gurevich’s model, the equation for H c 2 takes the form where a 0 = 2 w /λ 0 , a 1 = 1 + λ – /λ 0 , and a 2 = 1 – λ – /λ 0 , with λ – = λ 11 – λ 22 , w = λ 11 λ 22 – λ 12 λ 21 , and .…”

Superconductivity with a Violation of Pauli Limit and Evidences for Multigap in η-Carbide Type Ti4Ir2O

“…Such a deviation can be explained by multigap superconductivity, as observed in MgB 2 , [47] 2H-NbSe 2 , [48] iron-based superconductors, [6] and YRe 2 SiC. [49] Indeed, the 𝐻 c2 data is excellently reproduced by a two-band model developed by Gurevich, [50] as indicated by the purple line in Fig. 3(f).…”