Water-cycle mechanism for writing and erasing nanostructures at the LaAlO3/SrTiO3 interface

Nanoscale control of the metal-insulator transition in LaAlO3/SrTiO3 heterostructures can be achieved using local voltages applied by a conductive atomic force microscope (c-AFM) probe. One proposed mechanism for such process involves adsorbed H2O which dissociates into OH- and H+ which are then selectively removed by a biased AFM probe. To test this mechanism, writing and erasing experiments are performed in a vacuum AFM using various gas mixtures. Writing ability is suppressed in those environments where H2O is not present. The self-erasure process in air can be strongly suppressed by creating a modest vacuum or replacing the humid air with dry inert gas. These experiments provide strong constraints for theories of both the writing process as well as the origin of interfacial conductance. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3506509]