Abstract
We investigated the time and temperature dependence of photobleaching effects in single crystals by Raman spectroscopy and Monte Carlo simulations based on the asymmetric next-nearest-neighbor Ising model. In a temperature range between 40 and the bleaching slows down on cooling, displaying a pronounced change in dynamics around for . 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.
2 More- Received 14 November 2003
DOI:https://doi.org/10.1103/PhysRevB.70.014512
©2004 American Physical Society