Hybridization-controlled charge transfer and induced magnetism at correlated oxide interfaces

Area of Science:

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

Background:

• Classical band alignment at conventional material interfaces relies on electrochemical potential.
• Polar interfaces in oxides like LaAlO3/SrTiO3 can host novel 2D electron systems.
• Correlated oxides exhibit complex electronic orders (charge, orbital, spin) due to strong Coulomb interactions, posing challenges to classical models.

Purpose of the Study:

• Investigate charge transfer mechanisms at correlated oxide interfaces beyond traditional band alignment theories.
• Explore the role of metal-oxygen bond covalence in charge reconstruction.
• Demonstrate strategies for engineering novel electronic phases at oxide interfaces.

Main Methods:

• Utilized the perovskite nickelate (RNiO3) family as a model system.
• Probed charge reconstruction at interfaces with gadolinium titanate (GdTiO3).
• Employed X-ray absorption spectroscopy (XAS) to analyze electronic states and hybridization.

Main Results:

• Identified the energy to alter metal-oxygen bond covalence as a critical factor in charge transfer at correlated interfaces.
• Observed that hybridization effects, tuned by rare-earth (R) size, can impede charge transfer.
• Demonstrated that charge transfer induces a ferromagnetic-like state in the nickelate layer.

Conclusions:

• Charge transfer at correlated oxide interfaces is governed by covalence and hybridization, not solely electron affinity or polarity.
• Rare-earth size in RNiO3 offers a knob to tune hybridization and control charge transfer.
• This research provides a framework for designing novel 2D electronic systems and functional phases by manipulating doping and covalence.