Thickness dependent properties in oxide heterostructures driven by structurally induced metal-oxygen hybridization variations

TL;DR

This study reveals that thickness-dependent electronic phase transitions in oxide heterostructures are primarily driven by structural changes affecting metal-oxygen hybridization, rather than just confinement or symmetry breaking.

Contribution

It provides direct evidence linking layer-dependent orbital hybridization and octahedral tilts to electronic and magnetic properties in oxide heterostructures, highlighting interface structure engineering.

Findings

Reduced octahedral tilting enhances Curie temperature.

Thickness influences p-d hybridization and orbital structure.

Structural relaxation correlates with electronic and magnetic phase changes.

Abstract

Thickness driven electronic phase transitions are broadly observed in different types of functional perovskite heterostructures. However, uncertainty remains whether these effects are solely due to spatial confinement, broken symmetry or rather to a change of structure with varying film thickness. Here, we present direct evidence for the relaxation of oxygen 2p and Mn 3d orbital (p-d) hybridization coupled to the layer dependent octahedral tilts within a La2/3Sr1/3MnO3 film driven by interfacial octahedral coupling. An enhanced Curie temperature is achieved by reducing the octahedral tilting via interface structure engineering. Atomically resolved lattice, electronic and magnetic structures together with X-ray absorption spectroscopy demonstrate the central role of thickness dependent p-d hybridization in the widely observed dimensionality effects present in correlated oxide heterostructures.