Modulating Spin Polarization and Spin-Orbit Interaction by Submonolayer Engineering at LaAlO3/SrTiO3 Interfaces

Recently, the LaAlO3/SrTiO3 (LAO/STO) interface has been highlighted as a major platform for spintronics, and its fundamental control of spin properties, therefore, becomes a key issue for application of this system. Here, we present a study showing the modulation of magnetic two-dimensional electron gases (2DEGs) with simultaneously enhanced spin-orbit interaction at the interface of LAO/STO by inserting LaCoO3 submonolayers. At first, transport experiments provide evidence that Kondo behavior can be well controlled below about 13 K with the interlayer Co ions contributing as scattering centers. In addition, the systematic variation of the anomalous Hall effect obtained with increasing fraction of interfacial Co concentration below 10 K reveals that the spin polarization of 2DEGs is enhanced via submonolayer insertion. Simultaneously, we also observe an enlarged spin-orbit interaction at the buffered LAO/STO interface, resulting in a remarkably strong field-orientation-dependent magnetoresistance. Such tailored LAO/STO interfaces could potentially contribute to stronger spin-to-charge conversion responses and spin-torque measurements. Our observations indicate the subunit-cell insertion of functional layers to be a suitable route to tailor spin, orbital, and lattice interactions of the interfacial 2DEG, which makes the LAO/STO system an intriguing platform for spintronic applications.