Light-induced oxygen-ordering dynamics in (Y,Pr)Ba2Cu3O6.7: A Raman spectroscopy and Monte Carlo study

BAHRS, S; GONI, AR; THOMSEN, C; MAIOROV, B; NIEVA, G; FAINSTEIN, A

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

Año: 2004 vol. 70 p. 145121 - 145129

0163-1829

We investigated the time and temperature dependence of photobleaching effects in RBa2Cu3O7-delta single crystals (R=Y,Pr) by Raman spectroscopy and Monte Carlo simulations based on the asymmetric next-nearest-neighbor Ising model. In a temperature range between 40 and 300 K the bleaching slows down on cooling, displaying a pronounced change in dynamics around 160 K for R=Y. To model this behavior we extended the Ising model by introducing a single energy barrier which impedes oxygen movement in the plane unless the oxygen atoms are excited by light. We obtain a time- and temperature-dependent development of superstructures under illumination with the fastest change at intermediate model temperatures. The chain-fragment development in the simulation thus matches the experimental low-temperature dynamics of Raman photobleaching, providing further support for oxygen reordering in the chain plane being at the origin of Raman photobleaching and related effects.