Molecular beam epitaxy of superconducting (Rb,Ba)BiO3

Abstract

The simple cubic perovskite (Rb,Ba)BiO3 can be grown at temperatures below 350 °C by molecular beam epitaxy using a rf plasma atomic oxygen source. Films with superconducting onsets in resistivity as high as 27 K are obtained without annealing. The epitaxy proceeds in the normal (100) orientation on {100} SrTiO3, despite a 10% lattice mismatch. (110) epitaxy and spotty reflection high-energy electron diffraction (RHEED) patterns are obtained on {100} MgO substrates, despite the good lattice match for (100) growth. Streaked and spotty RHEED patterns have been obtained on either substrate. Sticking coefficients for bismuth depend on the growth conditions, indicating that the epitaxy is partially controlled by desorption kinetics.