Signatures of mesoscopic Jahn Teller polaron inhomogeneities in high-temperature superconductors

We analyse complementary experimental results in high-temperature superconducting cuprates from x-ray absorption fine structure (XAFS), inelastic neutron scattering (INS) and inelastic x-ray scattering (IXS), Raman spectroscopy (RS), infrared absorption spectroscopy and femtosecond optical spectroscopy in terms of the predictions of a specific fully quantum mechanical calculation of small polaron formation and internal dynamics (phonon-assisted local charge oscillations). These analyses support the scenario in which the pseudogap-associated temperature, T *, marks the onset of an inhomogeneous ground state with polarons, in agreement with several theoretical models which attempt to explain the origin of high-temperature superconductivity in doped cuprates. The change in dynamics, which is observed across the superconducting transition temperature, T c in XAFS, INS and RS, indicates an intimate link of the dynamics of these polarons with the mechanism of high-temperature superconductivity.