Confinement‐Enhanced Rashba Spin–Orbit Coupling at the LaAlO3/KTaO3 Interface via LaAlO3 Thickness Control

Superconductors with strong spin–orbit coupling (SOC) have attracted tremendous attention due to the great potential for realizing topological superconductivity and searching Majorana fermions. Recently, two‐dimensional (2D) superconductivity with a relatively high T c ≈ 2 K is observed in LaAlO 3 /KTaO 3 (111) and EuO/KTaO 3 (111) heterointerfaces. However, the experimental investigations of the SOC in the KTaO 3 (111)‐based heterointerfaces are still lacking. Herein, the Rashba SOC of LaAlO 3 /KTaO 3 (111) interfaces with varied LaAlO 3 thickness is studied. It is revealed that the spatial confinement of the 2D electron gas tuned by the LaAlO 3 thickness prominently enhances the SOC. The maximal Rashba spin‐splitting energy Δ so reaches ≈48 meV in this work, which is an extremely high value ever reported in oxide‐based conducting heterointerfaces.