Superconductivity in CeOBiS2 with cerium valence fluctuation

TL;DR

This study reports superconductivity in CeOBiS2 without doping, likely driven by cerium valence fluctuations, with zero resistivity observed below 1.2 K in both single and polycrystalline forms.

Contribution

It demonstrates superconductivity in CeOBiS2 without chemical doping, linked to cerium valence fluctuation, expanding understanding of unconventional superconductivity mechanisms.

Findings

CeOBiS2 exhibits zero resistivity below 1.2 K.

Superconductivity is suppressed by higher current density.

Superconductivity is likely induced by cerium valence fluctuation.

Abstract

Resistivities of single-crystalline as well as poly-crystalline samples of CeOBiS2 without fluorine doping were measured at temperatures down to 0.13 K, and were compared with those of poly-crystalline LaOBiS2 and PrOBiS2. Both poly-crystalline and single-crystalline CeOBiS2 exhibited zero resistivity below 1.2 K while poly-crystalline LaOBiS2 and PrOBiS2 did not show zero resistivity down to 0.13 K. Superconducting transition temperature of CeOBiS2 was reduced by increasing the applied current density. The superconductivity of CeOBiS2 without chemical doping is likely triggered by the carriers induced by the valence fluctuation between Ce3+ and Ce4+.