Superconductivity of Tin or Tellurium Doped Bismuth at Ultra Low Temperature

抄録

Ac magnetic susceptibility of Sn doped Bi (0.036–0.183 at%Sn) and Te doped Bi (0.289 at%Te) have been measured at low temperature down to 4.5 mK by the use of dilution refrigerator. Broad superconducting transition occurs below about 0.1 K, but no perfect Meissner effect is seen down to the measured lowest temperature. Magnitude of susceptibility decreases when the primary ac magnetic field increases or when dc magnetic field increases, although dependence on the latter is smaller than on the former. The same results are seen on the specimens of different concentrations of Sn except that the diamagnetic susceptibility becomes smaller as the concentration of Sn becomes smaller.