Large polarons as key quasiparticles in SrTiO3 and SrTiO3-based heterostructures

Abstract

Despite its simple structure and low degree of electronic correlation, SrTiO${}_3$ (STO) features collective phenomena linked to charge transport and, ultimately, superconductivity, that are not yet fully explained. Thus, a better insight in the nature of the quasiparticles shaping the electronic and conduction properties of STO is needed. We studied the low energy excitations of bulk STO and of the LaAlO${}_3$/SrTiO${}_3$ two dimensional electron gas (2DEG) by Ti L${}_3$ edge resonant inelastic x-ray scattering. In all samples, we find the hallmark of polarons in the form of intense $dd$+phonon excitations, and a decrease of the LO3-mode electron-phonon coupling when going from insulating to highly conducting STO single crystals and heterostructures. Both results are attributed to the dynamic screening of the large polaron self-induced polarization, showing that the low temperature physics of STO and STO-based 2DEGs is dominated by large polaron quasiparticles.

5 pages, 4 figures

References in corpus (8)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Superconductivity in single-layer films of FeSe with a transition temperature above 100 K
• Theory of spin-orbit coupling at LaAlO3/SrTiO3 interfaces and SrTiO3 surfaces
• Electron-phonon interaction and charge carrier mass enhancement in SrTiO3
• Polarons from first principles, without supercells
• EDRIXS: An open source toolkit for simulating spectra of resonant inelastic x-ray scattering
• Generalization of the Franck-Condon model for phonon excitations by resonant inelastic X-ray scattering
• Raman and fluorescence contributions to resonant inelastic soft x-ray scattering on LaAlO${}_3$/SrTiO${}_3$ heterostructures

Cited by in corpus (13)

• Orientation-dependent electron-phonon coupling in interfacial superconductors LaAlO3/KTaO3
• Universal Structural Influence on the 2D Electron Gas at SrTiO${}_3$ Surfaces
• Description of resonant inelastic x-ray scattering in correlated metals
• Probing electron-phonon interactions away from the Fermi level with resonant inelastic x-ray scattering
• Doping-dependence of the electron-phonon coupling in two families of bilayer superconducting cuprates
• Theory of electron-phonon interactions in extended correlated systems probed by resonant inelastic x-ray scattering
• Electronic structure of the frustrated diamond lattice magnet NiRh${}_2$O${}_4$
• Ground state features and spectral properties of large polaron liquids from low to high charge densities
• Two-Dimensional Charge Localization at the Perovskite Oxide Interface
• Evolution of orbital excitations from insulating to superconducting MgTi${}_2$O${}_4$ films
• Orbital inversion and emergent lattice dynamics in infinite layer CaCoO${}_2$
• The influence of phonon symmetry and electronic structure on the electron-phonon coupling momentum dependence in cuprates
• Absence of localized $5d^1$ electrons in KTaO${}_3$ interface superconductors