Superconductivity in boron-doped SiC

We report superconductivity in heavily boron-doped bulk silicon carbide related to the diamond structure. The compound exhibits zero resistivity and diamagnetic susceptibility below a critical temperature T-c of similar to 1.4K, and an effective boron doping concentration higher than 10(21) cm(-3). We present the H-T phase diagram of this new superconducting compound determined from AC susceptibility. In finite DC magnetic fields a clear hysteresis was observed between cooling and subsequent warming runs. This indicates, in contrast with the type-II superconductivity in boron-doped diamond and silicon, that a type-I superconductivity with a critical field H-c(0) of about 100 Oe is realized in boron-doped SiC. Moreover, the specific-heat shows a clear jump at Tc, demonstrating bulk nature of the superconductivity.