Interlayer coupling and electronic structure of misfit-layered bismuth-based cobaltites

Abstract

The ${[{\mathrm{Bi}}_{2}{M}_{2}{\mathrm{O}}_{4}]}_{p}{\mathrm{CoO}}_{2}$ materials ($M=\text{Ca}$, Sr, and Ba) were studied to clarify the effect of the lattice incommensurability on electronic properties using angle-resolved photoemission spectroscopy and transmission electron microscopy (TEM). Results show that the insulating behavior is characterized by a spectral weight for binding energies higher than 2.0 eV. Moreover, the spectral shape is modified as a function of the incident photon energy, demonstrating a close relationship between the electrical properties and interlayer coupling. TEM results show that the effect of the lattice mismatch differs for different misfit parameters $p$. We therefore conclude that the carrier concentration and the chemical environment at the misfit interface, which depend on the degree of incommensurability, mutually determine the electronic properties of the system.