Planar spin valves are mesoscale spintronics architectures in which spin currents are injected, transported, manipulated and detected. Traditionally, spin injection and detection are achieved with metallic ferromagnetic contacts while spins are transported in a high mobility channel based on e.g. graphene or semiconductors. This unavoidably requires interfaces between different materials, with a detrimental impact on device performance. In addition, how spins are generated and detected is inherently fixed by the electronic structure of the materials. In our paper just out in Nano Letters, we demonstrate the electric-field control of spin current generation and detection in planar nanodevices free from ferromagnets and only based on a SrTiO3 two-dimensional electron gas (2DEG) with Rashba spin-orbit coupling. The spin current is generated by the direct 2D spin Hall effect from a charge current running in the 2DEG, transported through the device and reconverted into a charge current by the inverse 2D spin Hall effect. By adjusting the Fermi level position with a gate voltage we tune the generated and detected spin polarization and relate it to the complex multiorbital band structure of the 2DEG. These findings highlight the potential of quantum oxide materials for future all-electric spin-based logic.
This work was performed in collaboration with Spintec in Grenoble and LPS in Orsay.
Electric-Field Control of Spin Current Generation and Detection in Ferromagnet-Free SrTiO3-Based Nanodevices
Felix Trier, Diogo C. Vaz, Pierre Bruneel, Paul Noël, Albert Fert, Laurent Vila, Jean-Philippe Attané, Agnès Barthélémy, Marc Gabay, Henri Jaffrès, Manuel Bibes
Nano Lett. 20, 395-401 (2020)