Conduction at domain walls in oxide multiferroics

Domain walls may play an important role in future electronic devices, given their small size as well as the fact that their location can be controlled. Here, we report the observation of room-temperature electronic conductivity at ferroelectric domain walls in the insulating multiferroic BiFeO3. The origin and nature of the observed conductivity are probed using a combination of conductive atomic force microscopy, high-resolution transmission electron microscopy and first-principles density functional computations. Our analyses indicate that the conductivity correlates with structurally driven changes in both the electrostatic potential and the local electronic structure, which shows a decrease in the bandgap at the domain wall. Additionally, we demonstrate the potential for device applications of such conducting nanoscale features. Correlated oxide systems are an exciting and challengingarea of condensed-matter research, with their interactingand competing charge, spin, orbital and lattice degrees of freedom forming new electronic and magnetic phases1,2. These phases can be controlled through stress, optical excitation and electric and magnetic fields and have great potential for applications in the fields of spintronics, information storage and communications. Among the correlated oxides, the multiferroics, which show more than one type of ferroic order in the same phase, are attracting particular interest3–6. The defining characteristic o