Coexistence of trapped and free excess electrons in SrTiO3

Abstract

The question whether excess electrons in SrTiO3 form free or trapped carriers is a crucial aspect for the electronic properties of this important material. This fundamental ambiguity prevents a consistent interpretation of the puzzling experimental situation, where results support one or the other scenario depending on the type of experiment that is conducted. Using density functional theory corrected with an on-site Coulomb interaction U, it is established that excess electrons form small polarons if the electron density is higher than ~ 1%. For densities below this critical value, the electrons stay delocalized or become large polarons. Our modeling of oxygen deficient SrTiO3 provides an alternative picture with respect to previous theoretical studies endowing firm evidence for the observed, temperature-driven metal-insulator transition in samples with homogeneously distributed oxygen vacancies. Small polarons confined to Ti(3+) sites are immobile at low temperature but can be thermally activated into a conductive state.

5 pages, 3 figures

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Cited by in corpus (25)

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• The effect of intrinsic point defects on ferroelectric polarization behavior of SrTiO${}_3$
• Zn vacancy as a polaronic hole trap in ZnO
• Surface magnetism of strontium titanate
• Engineering two-dimensional electron gases at the (001) and (101) surfaces of TiO2 anatase using light
• Band Versus Polaron: Charge Transport in Antimony Chalcogenides
• Coexistence of polar distortion and metallicity in PbTi1-xNbxO3
• Mass enhancement in 3d and s-p perovskites from symmetry breaking
• Small Polarons in Transition Metal Oxides
• Universal Structural Influence on the 2D Electron Gas at SrTiO${}_3$ Surfaces
• Machine Learning for Exploring Small Polaron Configurational Space
• Oxygen Vacancies in Strontium Titanate: a DFT+DMFT study
• Magnetic properties of bilayer Sr${}_3$Ir${}_2$O${}_7$: role of epitaxial strain and oxygen vacancies
• Excitations in a spin-polarized tow-dimensional electron gas
• Engineering ultra-strong electron-phonon coupling and nonclassical electron transport in crystalline gold with nanoscale interfaces
• Polaronic nature of a muonium-related paramagnetic center in SrTiO${}_3$
• Single spin-polarised Fermi surface in SrTiO${}_3$ thin films
• All-coupling polaron optical response: analytic approaches beyond the adiabatic approximation
• Direct observation of two-dimensional small polarons at correlated oxide interface
• Self-consistent DFT+$U$+$V$ study of oxygen vacancies in SrTiO${}_3$
• Dynamic defect correlations dominate activated electronic transport in SrTiO3
• Phenomenological plasmon broadening and relation to the dispersion
• Dynamic correlations in the highly dilute 2D electron liquid: loss function, critical wave vector and analytic plasmon dispersion