Orbital engineering in symmetry-breaking polar heterostructures

Area of Science:

• Condensed Matter Physics
• Materials Science
• Solid-State Chemistry

Background:

• Electronically correlated oxides exhibit complex behaviors due to strong electron-electron interactions.
• Traditional methods like strain or confinement have limitations in precisely controlling orbital properties.
• Atomically layered heterostructures offer a platform for novel interfacial phenomena.

Purpose of the Study:

• To demonstrate a novel method for modifying orbital occupations and symmetries in correlated oxides.
• To investigate the role of charge transfer and inversion symmetry breaking in orbital tuning.
• To establish a general approach for engineering electronic properties in oxide heterostructures.

Main Methods:

• Experimental synthesis of atomically layered heterostructures (LaTiO3-LaNiO3-LaAlO3).
• X-ray absorption spectroscopy to probe electronic structure.
• Ab initio theoretical calculations to understand charge transfer and polar fields.

Main Results:

• Achieved substantial modification of orbital occupations and symmetries.
• Demonstrated significant electron transfer and polar field effects.
• Observed a ~50% change in Ni d orbital occupation, removing orbital degeneracy.
• Approached a single-band Fermi surface electronic configuration.

Conclusions:

• Atomically layered heterostructures provide a powerful route for orbital engineering in correlated oxides.
• The demonstrated method is robust and tunable by material selection.
• This approach offers a general strategy for designing novel electronic systems with tailored orbital configurations.