Persistence of small polarons into the superconducting phase of Ba${}_{1-x}$K${}_x$BiO${}_3$

Abstract

Bipolaronic superconductivity is an exotic pairing mechanism proposed for materials like Ba${}_{1-x}$K${}_x$BiO${}_3$ (BKBO); however, conclusive experimental evidence for a (bi)polaron metallic state in this material remains elusive. Here, we combine resonant inelastic x-ray and neutron total scattering techniques with advanced modelling to study the local lattice distortions, electronic structure, and electron-phonon coupling ($e$-ph) in BKBO as a function of doping. Data for the parent compound ($x=0$) indicates that the electronic gap opens in predominantly oxygen-derived states strongly coupled to a long-range ordered breathing distortion of the oxygen sublattice. Upon doping, short-range breathing distortions and sizable ($e$-ph) coupling persist into the superconducting regime ($x=0.4$). Comparisons with exact diagonalization and determinant quantum Monte Carlo calculations further support this conclusion. Our results provide compelling evidence that BKBO's metallic phase hosts a liquid of small (bi)polarons derived from local breathing distortions of the lattice, with implications for understanding the low-temperature superconducting instability

References in corpus (33)

• Superconductivity in Iron Compounds
• Resonant Inelastic X-ray Scattering Studies of Elementary Excitations
• Theory of Intertwined Orders in High Temperature Superconductors
• Probing the Low-Energy Electronic Structure of Complex Systems by ARPES
• Site-selective Mott transition in rare earth nickelates
• Ground state oxygen holes and the metal-insulator transition in the negative charge transfer rare-earth nickelates
• Charge disproportionation without charge transfer in the rare-earth nickelates as a possible mechanism for the metal-insulator transition
• Correlation-enhanced electron-phonon coupling: Applications of GW and screened hybrid functional to bismuthates, chloronitrides, and other high Tc superconductors
• Incoherent transport across the strange metal regime of highly overdoped cuprates
• Polaronic hole-trapping in doped $\mathrm{BaBi}{\mathrm{O}}_3$
• The Role of Lattice Coupling in Establishing Electronic and Magnetic Properties in Quasi-One-Dimensional Cuprates
• Determining the Electron-Phonon Coupling Strength in Correlated Electron Systems from Resonant Inelastic X-ray Scattering
• Directly characterizing the relative strength and momentum dependence of electron-phonon coupling using resonant inelastic x-ray scattering
• Hybridization effects and bond-disproportionation in the bismuth perovskites
• Discovery of Superconductivity in (Ba,K)SbO${}_3$
• Unveiling the superconducting mechanism of Ba${}_{0.51}$K${}_{0.49}$BiO${}_3$
• Momentum-Resolved Electronic Structure of the High-$T_c$ Superconductor Parent Compound BaBiO${}_3$
• Oxygen holes and hybridization in the bismuthates
• Quantum Monte Carlo study of lattice polarons in the two-dimensional multi-orbital Su-Schrieffer-Heeger model
• Demonstration of resonant inelastic X-ray scattering as a probe of exciton-phonon coupling
• A hybrid Monte Carlo study of bond-stretching electron-phonon interactions and charge order in BaBiO${}_3$
• Generalization of the Franck-Condon model for phonon excitations by resonant inelastic X-ray scattering
• Charge order above room-temperature in a prototypical kagome superconductor La(Ru${}_{1-x}$Fe${}_x$)${}_3$Si${}_2$
• SmoQyDQMC.jl: A flexible implementation of determinant quantum Monte Carlo for Hubbard and electron-phonon interactions (version 2.0 release)
• Local inversion-symmetry breaking in a bismuthate high-$T_c$ superconductor
• Dynamical tuning of the chemical potential to achieve a target particle number in grand canonical Monte Carlo simulations
• Beyond the single-site approximation modeling of electron-phonon coupling effects on resonant inelastic X-ray scattering spectra
• Bond versus charge disproportionation in the bismuth perovskites
• Polaron and bipolaron tendencies in a semiclassical model for hole-doped bismuthates
• Strong- to weak-coupling superconductivity in high-$T_c$ bismuthates: revisiting the phase diagram via $\mu$SR
• Theory of electron-phonon interactions in extended correlated systems probed by resonant inelastic x-ray scattering
• Large oxygen-isotope effect in Sr_{0.4}K_{0.6}BiO_{3}: Evidence for phonon-mediated superconductivity
• Temperature dependence of the magnetic penetration depth in BKBO superconductor

Cited by in corpus (1)

• The influence of phonon symmetry and electronic structure on the electron-phonon coupling momentum dependence in cuprates