Superconductivity of F-substituted LnOBiS₂ (Ln=La, Ce, Pr, Nd, Yb) compounds

Abstract

Polycrystalline samples of F-substituted LnOBiS₂ (Ln = La, Ce, Pr, Nd, Yb) compounds were synthesized by solid-state reaction. The samples were characterized by X-ray diffraction measurements and found to have the ZrCuSiAs crystal structure. Electrical resistivity and magnetic susceptibility measurements were performed on all of the samples and specific heat measurements were made on those with Ln = La, Ce, and Yb. All of these compounds exhibit superconductivity in the range 1.9 K–5.4 K, which has not previously been reported for the compounds based on Ce, Pr, and Yb. The YbO_0.5F_0.5BiS₂ compound was also found to exhibit magnetic order at ∼2.7 K that apparently coexists with superconductivity below 5.4 K.

Keywords:

• superconducting materials
• rare earth compounds
• electrical resistivity
• specific heat

Acknowledgements

The authors gratefully acknowledge the support of the US Air Force Office of Scientific Research – Multidisciplinary University Research Initiative under Grant No. FA9550-09-1-0603 (superconductivity search) and the US Department of Energy under Grant No. DE-FG02-04-ER46105 (characterization and physical properties measurements).