Unconventional Co-existence of insulating nano-regions and conducting filaments in reduced SrTiO3 : mode softening, local piezoelectricity, and metallicity

摘要: Doped SrTiO3 becomes a metal at extremely low doping concentrations n and is even superconducting < 1020 cm−3, with the transition temperature adopting dome-like shape increasing carrier concentration. In this paper it shown within polarizability model from first principles calculations that up to well-defined concentration nc transverse optic mode softening takes place together polar nano-domain formation, which provides evidence of inhomogeneity two-component type behavior metallicity coexisting polarity. Beyond region, conventional formed where superconductivity as well absent. For ≤ effective electron-phonon coupling follows temperature. Effusion measurements, macroscopic nanoscopic conductivity indicate distribution oxygen vacancies local inhomogeneous, concluded stems filaments are embedded in matrix long nc.