Novel Electronic Structure Induced by a Highly Strained Oxide Interface with Incommensurate Crystal Fields

The misfit oxide, Bi(2)Ba(1.3)K(0.6)Co(2.1)O(7.94), made of alternating rocksalt-structured [BiO/BaO] layers and hexagonal CoO(2) layers, was studied by angle-resolved photoemission spectroscopy, revealing the electronic structure of a highly strained oxide interface. We found that low-energy states are confined within individual sides of the interface, but scattered by the incommensurate crystal field from the other side. Furthermore, the high strain on the rocksalt layer induces large charge transfer to the CoO(2) layer, and a novel effect, the interfacial enhancement of electron-phonon interactions, is discovered.