SrTiO₃-based 2-dimensional electron gases for ultralow power spintronics

SrTiO₃ (STO) 2DEG may be exploited to interconvert spin and charge currents with high efficiencies. 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 conversion amplitude. This can be related to the band structure through ARPES experiment and tight-binding calculations. I will present results from both spin-charge conversion where spins are injected by spin pumping in a FMR cavity and detected as a transverse voltage¹, and from charge-spin conversion probed through the bilinear magnetoresistance (BMR) effect. Through a semi-classical model, the analysis of the BMR amplitude yields a measure of the Rashba coefficient². In a second part, I will present gate-controlled, all-electrical spin current generation and detection in planar nanodevices free from ferromagnets³. Finally, I will propose a new approach to achieve a non-volatile control of spin-charge interconversion with Rashba 2DEGs based on ferroelectricity rather than ferromagnetism, that may pave the way to an entirely new family of ultralow power spintronics devices⁴.

¹ Nat. Mater. 18, 1187 (2019) ; 2 PR Mater 4, 071001 (2020) ³ Nano Lett. 20, 395 (2020) ; ⁴ Nature 580, 483 (2020)