Superconductivity in the Narrow-Gap Semiconductor CsBi₄Te₆

Superconductivity was discovered in the narrow-gap semiconductor CsBi₄Te₆. A superconducting transition around 4.4 K was observed for p-type samples in temperature-dependent resistivity and magnetic susceptibility data. Stoichiometric CsBi₄Te₆ is not a superconductor. A remarkably high critical field of ∼10 T was estimated from the field-dependent resistivity data. The strongly anisotropic CsBi₄Te₆ system is monoclinic and the first member of a larger homologous series Cs₄[Bi_2n+4Te_3n+6] that exhibits unconventional superconductivity, suggesting that proper doping of the homologous series may create a novel class of superconductors from semiconductors.