Effect of Two-Dimensional Crystal Orbitals on Fermi Surfaces and Electron Transport in Three-Dimensional Perovskite Oxides.

ABSTRACT

Perovskite oxides are candidate materials in catalysis, fuel cells, thermoelectrics, and electronics, where electronic transport is vital to their use. While the fundamental transport properties of these materials have been heavily studied, there are still key features that are not well understood, including the temperature-squared behavior of their resistivities. Standard transport models fail to account for this atypical property because Fermi surfaces of many perovskite oxides are low-dimensional and distinct from traditional semiconductors. In this work, the low-dimensional Fermi surfaces of perovskite oxides are chemically interpreted in terms of two-dimensional crystal orbitals that form the conduction bands. Using SrTiO3 as a case study, the d/p-hybridization that creates these low-dimensional electronic structures is reviewed and connected to its fundamentally different electronic properties. A low-dimensional band model explains several experimental transport properties, including the temperature and carrier-density dependence of the effective mass, the carrier-density dependence of scattering, and the temperature dependence of resistivity. This work highlights how chemical bonding influences semiconductor transport.