We report on the metastable photo-bleaching of the 2.15 eV yellow Raman resonance in oxygen deficient YBa2Cu3Ox (x = 6.35-6.87), extending investigations by Wake et al. (Phys. Rev. Lett., 1991, 67, 3728) for x ≈ 1. Polarization, x dependence and phonon spectra indicate that the resonance is localized at oxygen vacancies in long CuO-chains. The resonance is thermally reactivated from the metastable bleached state with a relaxation time τ∼exp[Δ/kBT] with Δ ≈ 1 eV. The resulting temperature dependent equilibrium resonance intensity essentially mirrors the oxygen superstructure disordering around T* ≈ 100°C observed in the same crystals by hard X-ray diffraction, thus offering a new effective probe of chain-oxygen dynamics in YBa2Cu3Ox.
ASJC Scopus subject areas
- 化学 (全般)