  Oxide-based two-dimensional electron gases (2DEGs) have generated significant
interest due to their potential for discovering novel physical properties.
Among these, 2DEGs formed in KTaO3 stand out due to the recently discovered
crystal face-dependent superconductivity and large Rashba splitting, both of
which hold potential for future oxide electronics devices. In this work,
angle-resolved photoemission spectroscopy is used to study the electronic
structure of the 2DEG formed at the (110) surface of KTaO3 after deposition of
a thin Al layer. Our experiments revealed a remarkable anisotropy in the
orbital character of the electron-like dispersive bands, which form a Fermi
surface consisting of two elliptical contours with their major axes
perpendicular to each other. The measured electronic structure is used to
constrain the modeling parameters of self-consistent tight-binding slab
calculations of the band structure. In these calculations, an anisotropic
Rashba splitting is found with a value as large as 4 meV at the Fermi level
along the [-110] crystallographic direction. This large unconventional and
anisotropic Rashba splitting is rationalized based on the orbital angular
momentum formulation. These findings provide insights into the interpretation
of spin-orbitronics experiments and help to constrain models for
superconductivity in the KTO(110)-2DEG system.
