Possible multiband superconductivity in the quaternary carbide YRe2SiC

We report for the first time the occurrence of superconductivity in the quaternary silicide carbide YRe₂SiC with T_c ≈ 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 T_c confirms that superconductivity is a bulk phenomenon, while a second feature in the heat capacity near 0.5T_c combined with the unusual temperature dependence of the upper critical field H_c2(T) indicate the presence of a multiband superconducting state. Additionally, the linear dependence of the lower critical field H_c1 with temperature resemble the behavior found in compounds with unconventional pairing symmetry. Band structure calculations reveal that 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.