A New Quasi-One-Dimensional Ternary Molybdenum Pnictide Rb_2Mo_3As_3 with Superconducting Transition at 10.5 K

We report superconductivity in a new ternary molybdenum pnictide Rb_2Mo_3As_3, synthesized via the solid state reaction method. Powder x-ray diffraction analysis reveals a hexagonal crystal structure with space group P\bar6m2 (No. 187), and the refined lattice parameters are a = 10.431(5) Å, c = 4.460(4) Å. SEM images show rod-like grains with good ductility, confirming a quasi-one-dimensional (Q1D) structure. Electrical resistivity and dc magnetic susceptibility characterizations exhibit superconductivity with an onset of T_\rm c=10.5 K. The upper critical field of Rb_2Mo_3As_3 is estimated to be 28.2 T at zero temperature, providing an evidence of possible unconventional superconductivity. Our recent discovery of MoAs-based superconductors above 10 K provides a unique platform for the study of exotic superconductivity in 4d electron systems with Q1D crystal structures.