Anisotropic conductance at improper ferroelectric domain walls

Domain walls in ferroelectric oxides hold great potential for the development of new device paradigms in oxide nanoelectronics due to their field-tunable functionality. They are also of fundamental interest for studies of ferroic and low-dimensional systems physics. We investigate the electronic conductance of ferroelectric domain walls in the improper ferroelectric ErMnO3. We show that the conductance is a continuously tunable function of the domain wall orientation, with a range of an order of magnitude. We explain the observed behavior using first-principles density functional and phenomenological theories, and relate it to the extraordinary stability of the inherent head-to-head and tail-to-tail domain walls in hexagonal manganites, which is a direct consequence of the improper ferroelectric character of these materials.