The spin texture in a SrTiO₃(111) two-dimensional electron gas

We report the observation of a bilinear magnetoelectric resistance (BMER) signal in the d-orbital two-dimensional electron gas (2DEG) at the SrTiO₃ (STO) (111) surface, demonstrating a spin-splitting. We show that our BMER measurements reveal a three-fold symmetric out-of-plane spin component that breaks the six-fold symmetry of the 2DEG subband dispersion, and an in-plane spin component locked perpendicularly to the momentum. By performing tight-binding supercell calculations based on the relativistic density functional theory of the STO bulk band structure, we find that this 3D spin texture is fully described by the effects of confinement of the STO t_2g conduction band in the (111) plane. We also show that the BMER can be substantially tuned through oxygen vacancy doping, electrostatic gating and temperature variation. Our findings highlight the untapped potential of SrTiO₃ (111) based 2DEGs as a playground for spintronic applications.