  Single crystals of In-doped PbBi2Te4 are synthesized via a conventional
solid-state method. Chemical analysis and hall measurements indicate that In
replaces Pb, introducing n-type carriers, creating Pb1-xInxBi2Te4. A
superconducting transition is observed with a maximum transition temperature
around 2.06 K for Pb1-xInxBi2Te4. Field dependent transport measurements reveal
type-II superconductivity and yield a maximum upper critical field around 1.55
T. Thermodynamic data indicates bulk superconductivity in the BCS weak coupling
limit. Our findings establish an ambient-pressure superconducting system in the
AM2X4 family, and doped PbBi2Te4 as a promising platform for the study of
topological superconductivity.
