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. 18, 1187 (2019)
See also the News item on Eureka Alert.