  Besides the cuprate superconductors lead-doped barium bismuthate still
attracts intense interest concerning its relatively high critical temperature
and the nature of its superconductivity in vicinity to a charge density wave
ordered topological insulator. Here we present bilayers of barium bismuthate
and barium leadate and find two-dimensional superconductivity at their
interfaces well described by current-voltage characteristics compatible with a
Berezinskii-Kosterlitz-Thouless transition. Magneto-transport studies
independently prove the two-dimensional character of the superconducting
properties in these bilayers. The particular dependence of the superconducting
transition temperature on the thickness of the barium leadate top layer
suggests the formation of the superconducting state to be strain-induced
through the interface.
