Polar metals, a category of materials exhibiting the unexpected coexistence of polar structural distortion and metallicity, have attracted considerable research interest. Despite several experimental studies, the effect of polar distortions on the electronic structure (such as orbital configuration) of polar metals remains unclear. Here, we investigate the electronic band structure, crystal-field splitting, and orbital configuration of an artificial two-dimensional polar metal based on the ${\mathrm{BaTiO}}_3/{\mathrm{SrTiO}}_3/{\mathrm{LaTiO}}_3$ heterostructure. The interfacial crystal and electronic structures were investigated by scanning transmission electron microscopy with atomic layer-resolved electron energy-loss spectroscopy. Resonant x-ray linear dichroism spectra revealed an anomalous orbital configuration with a unique sequence $(d_{xy}<d_{xz}/d_{yz}<d_{3z^2-r^2}<d_{x^2-y^2})$, where the in-plane and out-of-plane orbital sequence of the $t_{2g}$ and $e_g$ states is reversed. More importantly, the $t_{2g}$ orbitals are nearly degenerate, which is a characteristic feature of polar distortion. The nearly degenerate $t_{2g}$ orbitals and the altered orbital sequence arise from the competition between epitaxial strain and polar distortion. Our work demonstrates that the electronic structure of polar metals can be strongly modulated by polar distortions, providing a general route for designing quantum states with tailored orbital configurations.

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• Electronic structure
• Heterostructures
• Electron energy loss spectroscopy
• X-ray absorption spectroscopy
• X-ray magnetic linear dichroism