Novel electronic structure induced by a highly strained oxide interface with incommensurate crystal fields

TL;DR

This study reveals the detailed electronic structure of a highly strained misfit oxide interface, showing electron confinement, charge transfer, and enhanced electron-phonon interactions, which are crucial for designing functional oxide interfaces.

Contribution

It provides the first detailed electronic structure analysis of a highly strained oxide interface with incommensurate crystal fields using angle-resolved photoemission spectroscopy.

Findings

Electrons are confined within individual sides of the interface.

Large charge transfer occurs due to high strain on the rocksalt layer.

Interfacial enhancement of electron-phonon interactions is observed.

Abstract

The misfit oxide, Bi$_{2}$Ba$_{1.3}$K$_{0.6}$Co$_{2.1}$O$_{y}$, made of alternating rocksalt-structured [BiO/BaO] layers and hexagonal CoO$_{2}$ layers, was studied by angle-resolved photoemission spectroscopy. Detailed electronic structure of such a highly strained oxide interfaces is revealed for the first time. We found that under the two incommensurate crystal fields, electrons are confined within individual sides of the interface, and scattered by umklapp scattering of the crystal field from the other side. In addition, the high strain on the rocksalt layer raises its chemical potential and induces large charge transfer to the CoO$_{2}$ layer. Furthermore, a novel interface effects, the interfacial enhancement of electron-phonon interactions, is discovered. Our findings of these electronic properties lay a foundation for designing future functional oxide interfaces.