The Oxitronics team is part of the CNRS/Thales laboratory located within Thales Research and Technology in Palaiseau, France. Our main scientific interests are in oxide electronics, spintronics, multiferroics, ferroelectrics and oxide interfaces. This website contains information on our past and current research, our group members and our publications. See also our events page for information on workshops, schools, etc.
While spintronics has traditionally relied on ferromagnetic metals as spin generators and detectors, spin-orbitronics exploits the efficient spin-charge interconversion enabled by spin-orbit coupling in non-magnetic systems. This is providing new opportunities for devices, such as the MESO transistor proposed by Intel, that relies on writing of magnetic information through magnetoelectric coupling, and reading it by spin-charge conversion. For the latter, oxide 2DEGs are promising as their spin-charge conversion efficiency is large (see our earlier work with LaAlO3/SrTiO3 2DEGs). In a new paper just published in Nature Materials, we demonstrate a very large spin to-charge conversion effect in an high carrier-density SrTiO3 2DEG generated by the sputter-deposition of Al at room temperature, and map the dependence of this effect to the band structure (as measured by ARPES). We show that the conversion process is amplified by enhanced Rashba-like splitting due to orbital mixing, and in the vicinity of avoided band crossings with topologically non-trivial order. Our results indicate that oxide 2DEGs are strong candidates for spin-based information readout in novel memory and transistor designs, and emphasize the promise of topology as a new ingredient to expand the scope of complex oxides for spintronics.
This work was performed in collaboration with Spintec and CEA-Inacin Grenoble, the Martin-Luther-Universität Halle-Wittenberg, the LPEM at ESPCI Paris, the Laboratoire de Physique des Solides in Orsay, the University of Geneva and the Helmholtz-Zentrum Berlin.
Mapping spin-charge conversion to the band structure in a topological oxide two-dimensional electron gas
Diogo C. Vaz, Paul Noël, Annika Johansson, Börge Göbel, Flavio Bruno, Gyanendra Singh, Siobhan McKeown-Walker, Felix Trier, Luis M. Vicente-Arche, Anke Sander, Sergio Valencia, Pierre Bruneel, Manali Vivek, Marc Gabay, Nicolas Bergeal, Felix Baumberger, Hanako Okuno, Agnès Barthélémy, Albert Fert, Laurent Vila, Ingrid Mertig, Jean-Philippe Attané and Manuel Bibes
Nature Mater. doi: 10.1038/s41563-019-0467-4 (2019)
See also the News item on Eureka Alert.
After several years of effort, the Roadmap of Oxide Electronics is now on line. This document was put together within the COST TO-BE project coordinated by Fabio Miletto Granozio from CNR-SPIN in Naples, and supervised by Mariona Coll and Josep Fontcuberta from ICMAB in Barcelona and Nini Pryds from Denmark Technical University. It covers virtually all areas of oxide research, from nanoelectronics, power electronics, spintronics to photonics, and gives a critical view on the future development of the field. We are glad to be a part of it !
Towards Oxide Electronics: a Roadmap
M. Coll et al, Appl. Surf. Sci. 482, 1 (2019)
Our PhD student Lorenzo Vistoli (second from the left) won the “Invention/innovation award” at the Italian embassy during the “Journée de la recherche italienne” organized by the RéCIF (Réseau des Chercheurs Italiens en France), in honor of the 500th anniversary of Leonardo da Vinci’s birth. He won the first place in a competition for young Italian researchers, based on scientific merit and a poster presentation on potential innovative applications of their research.
Congratulations Lorenzo !
Transition metal perovskite oxides ABO3 have a very rich array of properties, and many compounds show an insulating behavior, despite the presence of a finite number of d electrons. This insulating character is often ascribed to dynamical electron correlations, but perovskites also possess structural distorsions that break symmetries, lift electronic degeneracies, and may thus also open band gaps. In a paper just published in Nature Communications, we show that if one allows symmetry-breaking energy-lowering crystal symmetry reductions and electronic instabilities within Density Functional Theory (DFT), one successfully and systematically recovers the trends in the observed band gaps, magnetic moments, type of magnetic and crystallographic ground state, bond disproportionation and ligand hole effects, Mott vs. charge transfer insulator behaviors, and the amplitude of structural deformation modes including Jahn-Teller in low temperature spin-ordered and high temperature disordered paramagnetic phases. Since DFT does not include dynamic correlations, our work suggests that they do not play a major role in determining the metallic or insulating nature of these oxides. In other words, ABO3 may be complicated, but they are not necessarily strongly correlated.
This work was performed in collaboration with the University of Colorado at Boulder.
Origin of band gaps in 3d perovskite oxides
Julien Varignon, Manuel Bibes & Alex Zunger, Nature Commun. 10, 1658 (2019)
Since April 1st, we have a new group member, Srijani Mallik. Srijani is from Kolkota, India and in our group she is a postdoctoral researcher within a FEINMAN project sponsored by Intel Corporation. The project will focus on the study of oxide interfaces as efficient spin-charge converters for new non-volatile spin-based logic.
Welcome Srijani !
Congratulations to our group member Manuel Bibes was is one of the 222 laureates of an Advanced Grant from the European Research Council (ERC). His project, FRESCO, will focus on spin-charge interconversion effects in spin-orbitronics architectures based on ferroelectric materials. Stay tuned for future results!