Nanoscale Control of an Interfacial Metal-Insulator Transition at Room Temperature*

We report the creation and erasure of nanoscale conducting regions at the interface between two insulating oxides, LaAlO$_{3}$ and SrTiO$_{3}$. Using voltages applied by a conducting atomic force microscope (AFM) probe, the buried LaAlO$_{3}$/SrTiO$_{3}$ interface is locally and reversibly switched between insulating and conducting states. Persistent field effects are observed using the AFM probe as a gate. Patterning of conducting lines with widths $\sim $3 nm, as well as arrays of conducting islands with densities $>$10$^{14}$/in$^{2}$, are demonstrated. The patterned structures are stable for $>$24 hours at room temperature.