ICMAB Seminar
\nBy Marta Gibe rt\, TU Wien\, Austria
\nAbstract:
\nAtomically engineered transition-metal-oxide heterostructures provide a v
ersatile platform for probing and tailoring magnetic properties at the ult
rathin limit and across interfaces. Materials that are both ferromagnetic
and insulating are rare\, yet they are key to spin-based and multifunction
al devices. We focus on the double-perovskite family RE₂NiMnO₆ (RE = r
are earth)\, one of the few families combining these two properties. La₂
NiMnO₆ exhibits a Curie temperature (Tc) of 280 K\, while Tc decreases linearly across the series with decreasing RE-radius.
In epitaxial RE₂NiMnO₆ thin films\, ferromagnetism survives d own to a few atomic layers\, and we show that ferromagnetism is also retai ned in free-standing membranes.
\nTo engineer the magnetic phase dia gram and probe interfacial coupling\, we fabricated atomically controlled superlattices (artificial stacks of alternating layers) of La₂NiMnO₆ a nd RE₂NiMnO₆ (RE = Nd\, Sm)\, compounds with distinct Curie temperatur es. Large-period superlattices display two separate magnetic transitions c haracteristic of the parent compounds. By contrast\, reducing the layer th ickness yields a single transition\, indicating that short-period heterost ructures behave as a single material. Interfaces also modify the magnetic exchange between neighboring layers.
\nElectron microscopy and first -principles calculations further reveal unequal antipolar cation displacem ents in these superlattices\, consistent with a net electric polarization and suggesting hybrid improper ferroelectricity. Combined with robust ferr omagnetism\, these results highlight double-perovskite heterostructures as a promising platform for multiferroic devices.
\nShort bio:
\nMarta Gibert studied Physics at the Autonomous Universit y of Barcelona. She obtained her PhD in 2009 at the Institute of Materials Science of Barcelona (ICMAB-CSIC). During her PhD\, she also did research internships at IFW Dresden (Germany)\, the University of Cambridge (UK) a nd Los Alamos National Laboratory (USA). She received the Physics Extraord inary PhD Award from the Autonomous University of Barcelona for her resear ch on chemically grown self-assembled oxide nanostructures. In 2010\, she joined the group of Prof. Triscone at the University of Geneva (Switzerlan d)\, first as a postdoctoral fellow and\, from 2013\, as maître assis tant. In February 2018\, she became a Swiss National Science Foundati on (SNSF) Professor at the Physics Institute of the University of Zurich ( Switzerland). Since September 2021\, she has been full professor at the In stitute of Solid State Physics at TU Wien (Vienna\, Austria).
\nIn 2 016\, Gibert was awarded the IBM Prize in Condensed Matter Physics of the Swiss Physical Society for “the study of unique magnetic coupling at oxi de interfaces”. In 2020\, she received the International Workshop on Oxi de Electronics (iWOE) prize for excellence in oxides research.
\nGib ert’s research is motivated by the fascinating physical properties of co mplex oxides\, including magnetism\, metal-insulator transitions and super conductivity. By growing atomically controlled thin films and artificially layered structures\, she focuses mainly on the electronic and magnetic pr operties that arise from reduced dimensionality and from reconstructions a t oxide interfaces. Understanding the subtle atomic-scale structural and e lectronic mechanisms that control interface physics in complex oxides is k ey to designing materials with tailored properties.
\nHosted by Gabriele de Luca\, from the MULFOX research group (Materials for Electroni cs Research Line)
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