Resonant Raman scattering and photoinduced metastability in oxygen-deficient YBa2Cu3Ox

We studied the photoinduced metastable states in oxygen-deficient YBa2Cu3Ox (Y123) (x = 6.35-6.87). The states are identified by the intensity depende nces of CuO-chain resonance on photo irradiation and temperature. Below roo m temperature (RT) the CuO-chain resonance can be completely suppressed by irradiation with visible light polarized along the CuO chains, indicating p hoto-assisted oxygen ordering. Above RT, the resonance intensity returns an d saturates at T > 100 degrees C. This behavior exactly reflects the temper ature dependence of chain oxygen ordering in the same crystals observed by hard X-ray diffraction. The stability of the photo-induced state is in agre ement with reported persistent photo-induced superconductivity effects. (C) 2000 Elsevier Science B.V. All rights reserved.