SrTiO3-based 2-dimensional electron gases for ultralow power spintronics: Has oxide electronics finally found its “killer app”?

17.12.2019 13:00 – 14:00

The ever increasing power consumption of Information and Communication Technology (ICT) systems  currently largely based on CMOS technology  is unsustainable in the mid-term1, which is driving major ICT manufacturers and the scientific community to actively search for alternative, more energy-efficient solutions for data storage and processing. One promising approach, proposed by Intel, is the so-called MESO transistor2 (for MagnetoElectric-Spin-Orbit), a spin-based non-volatile device in which magnetic information is written by a magnetoelectric element and read out by a spin-orbit element through the inverse spin Hall effect (ISHE) or the inverse Edelstein effect (IEE). The IEE occurs in systems with broken inversion symmetry such as the surface of topological insulators or in two-dimensional electron gases (2DEG) displaying Rashba spin-orbit coupling3. The IEE is particularly attractive because of superior spin to charge conversion efficiencies and of the higher resistance of 2DEGs compared to metals showing ISHE.
In this presentation, I will show that the 2DEG that forms at the interface of SrTiO3 (STO)4 with LaAlO35 or reactive metals such as Al6 may be exploited to interconvert spin and charge currents through the direct and inverse Edelstein effects with high efficiencies. In a first part, I will present spin to charge conversion experiments using the spin-pumping technique to inject a spin current in the 2DEG7,8. By applying a gate voltage, we tune the position of the Fermi level in the complex multi-orbital structure of STO, which results in a strong variation of the IEE amplitude with sign changes. This can be semi-quantitatively related to the band structure through a tight-banding modelling of the band structure measured by ARPES and semi-classical Boltzmann calculations. Importantly, a finite conversion effect persists at room temperature, with a figure-of-merit competitive for MESO-based electronics.
In a second part, I will present gate-controlled, all-electrical spin current generation and detection in planar nanodevices free from ferromagnets and only based on a STO 2DEG. Here, the spin current is generated by the direct 2D spin Hall effect9 from a charge current running in the 2DEG, transported through the device over several microns and reconverted into a charge current by the inverse 2D spin Hall effect.
Finally, I will present a new ferromagnet-free approach to achieve a non-volatile control of spin-charge interconversion with Rashba 2DEGs, that may pave the way to an entirely new family of ultralow power spintronics devices10.

Lieu

Bâtiment: Ecole de Physique

Auditoire Stueckelberg

entrée libre