Publication Type:Journal Article
Source:Nature Materials, Nature Publishing Group, Volume 11, Number 4, p.284-288 (2012)
Keywords:Degrees of freedom (mechanics), density functional theory, Domain wall orientations, Domain walls, Electric fields, Environmental friendliness, External electric field, Ferroelectric materials, ferroelectricity, Insulator metal transition, Metal insulator transition, Phenomenological theory, Strong electronic correlations, Tail-to-tail domain walls, Transition metal compounds, Transition metals, Transition-metal oxides
Transition metal oxides hold great potential for the development of new device paradigms because of the field-tunable functionalities driven by their strong electronic correlations, combined with their earth abundance and environmental friendliness. Recently, the interfaces between transition-metal oxides have revealed striking phenomena, such as insulator-metal transitions, magnetism, magnetoresistance and superconductivity. Such oxide interfaces are usually produced by sophisticated layer-by-layer growth techniques, which can yield high-quality, epitaxial interfaces with almost monolayer control of atomic positions. The resulting interfaces, however, are fixed in space by the arrangement of the atoms. Here we demonstrate a route to overcoming this geometric limitation. We show that the electrical conductance at the interfacial ferroelectric domain walls in hexagonal ErMnO3 is a continuous function of the domain wall orientation, with a range of an order of magnitude. We explain the observed behaviour using first-principles density functional and phenomenological theories, and relate it to the unexpected stability of head-to-head and tail-to-tail domain walls in ErMnO3 and related hexagonal manganites. As the domain wall orientation in ferroelectrics is tunable using modest external electric fields, our finding opens a degree of freedom that is not accessible to spatially fixed interfaces. © 2012 Macmillan Publishers Limited. All rights reserved.
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