Novel supercell compounds of layered Bi-Rh-O with $p$-type metallic conduction materialized as a thin film form

Layered oxides have been intensively studied due to their high degree of freedom in designing various electromagnetic properties and functionalities. While Bi-based layered supercell (LSC) compounds [Bi$_n$O$_{n+\delta}$]-[$M$O$_2$] ($M$ = Mn, Mn/Al, Mn/Fe, or Mn/Ni; $n=2, 3$) are a group of prospective candidates, all of the reported compounds are insulators. Here, we report on the synthesis of two novel metallic LSC compounds [Bi$_{n}$O$_{n+\delta}$]-[RhO$_2$] ($n=2, 3$) by pulsed laser deposition and subsequent annealing. With tuning the thickness of the sublattice from Bi$_2$O$_{2+\delta}$ to Bi$_3$O$_{3+\delta}$, a dimensionality-dependent electrical transport is revealed from a conventional metallic transport in $n=2$ to a localized transport in $n=3$. Our successful growth will be an important step for further exploring novel layered oxide compounds.