Metal-to-insulator transition in a columnar nanocomposite oxide*

The capability of tuning lattice strain, composition, and dimensionality in epitaxial film growth provide a new avenue of exploring new functionality in correlated electron materials. Here we demonstrated a chemical ratio controlled metal-insulator transition in the nanocomposite films of V$_{2}$O$_{3}$-La$_{2/3}$Sr$_{1/3}$MnO$_{3}$ (LSMO) grown on LaAlO$_{3}$ (111) substrate through alternative deposition of LSMO and V$_{2}$O$_{3}$. A V-Mn ion exchange between V$_{2}$O$_{3}$ and LSMO occurs during the growth and results in the formation of nanoscale and vertically columnar-like insulating Mn$_{2}$O$_{3}$ and metallic La$_{1-x}$Sr$_{x}$VO$_{3}$ composite, as qualitatively revealed by scanning transmission electron microscopy. As determined by transport measurement, a metal-insulator transition is found in the composite films, which depends on the ratio of deposition time of V$_{2}$O$_{3}$ to LSMO.