The transport properties of domain walls in oxygen deficient multiferroic YMnO3 single crystals
have been probed using conductive atomic force microscopy and piezoresponse force microscopy.
Domain walls exhibit significantly enhanced conductance after being poled in electric fields,
possibly induced by oxygen vacancy ordering at domain walls. The electronic conduction can be
understood by the Schottky emission and Fowler-Nordheim tunnelling mechanisms. Our results
show that the domain wall conductance can be modulated through band structure engineering by
manipulating ordered oxygen vacancies in the poling fields.