Growth and Characterization of ROBiS 2 High-Entropy Superconducting Single Crystals.

A series of high-entropy superconductors, ROBiS ₂ (R = La + Ce + Pr + Nd + Sm), have been successfully grown in the form of single crystals using CsCl flux. The obtained single crystals have a platelike shape with a size of 0.5-2.0 mm and a thickness of 70-450 μm, and they are cleavable along the c -plane. The c -axis lattice constants of the obtained ROBiS ₂ single crystals have similar values of 13.47-13.57 Å. The Ce in the obtained ROBiS ₂ single crystals was in a mixed-valence state, comprising both Ce ³⁺ and Ce ⁴⁺ . On the other hand, Pr and Sm showed only the trivalent state. The superconducting transition temperatures of ROBiS ₂ single crystals were approximately 2-4 K. The superconducting transition temperature and superconducting anisotropies of R-site mixed high-entropy samples increased with a decrease in the mean ionic radius of the R-site. Moreover, a deviation in the tendency to exhibit superconducting properties was observed based on the difference in the R-site mixed entropy. R-site mixed entropy in ROBiS ₂ superconductors may affect their superconducting properties.
Competing Interests: The authors declare no competing financial interest.
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