Claribel Dominguez, in the group of Prof. Jean-Marc Triscone (UNIGE), currently working on the exciting field of “oxide interface physics”, received the iWOE26 poster prize for her research “Engineering electronic coupling of metal-insulator phases at SmNiO3/NdNiO3 interfaces”.
Nowadays, interfaces between different compounds are a recognized playground to manipulate the electronic phases of transition metal oxides. In the last years, control of the structural coupling of the oxygen sublattices during epitaxy synthesis is arising as a very powerful strategy to manipulate the states of matter in complex oxides.
“In order to get further inside into this topic, explains Claribel, as a model system we take SmNiO3 and NdNiO3 from the fascinating rare earth nickelate family RNiO3, well-known for their sharp metal-to-insulator transition (MIT) observed as a function of temperature. In bulk form, these two compounds show a MIT at two very different temperatures (400K and 200K, respectively). We create atomic-precision epitaxial superlattices that display, depending on the thickness of the individual layers, a single or double MIT. These heterostructures allows the origin of the coupling at such oxide interfaces to be studied. The key finding is that the length scale of the metal-insulator transition is not set by the length scale of the propagation of structural motifs (for instance Ni-O-Ni bond angles) across the interface between the two materials, which ab-initio calculations and TEM analyses suggest is minimal, but rather by the balance between the energy cost of having metallic-insulating phase boundaries and the bulk energetics. This result opens a new path for engineering functional properties in heterostructures that are not available in bulk. This represents a paradigm-shift in our understanding of oxide interfaces.”