Superconductivity and quantum oscillations in crystalline Bi nanowire

While bulk bismuth (Bi) is a semimetal, we have found clear evidence of superconductivity in 72 nm diameter crystalline Bi nanowire below 1.3 K. In a parallel magnetic field (H), the residual resistance of the nanowire below T(c) displays periodic oscillations with H, and the period corresponds to a superconducting flux quantum. This result indicates that the superconductivity originates from the cylindrical shell between Bi inner core and the surface oxide layer. Under a perpendicular H, the resistance in the superconducting state shows Shubnikov-de Haas (SdH)-like oscillations, a signature of a normal metal. These results suggest a novel coexistence of superconducting and metallic states in the temperatures well below T(c).