Abstract :
Transient reflectance changes are studied for a spin ladder system α′-NaV2O5 in the temperature range from 4 K to room temperature (RT), by means of femtosecond pump-and-probe measurements. A large response with a slow rise (3 ps) and a slow decay (>400 ps) is found only below 34 K, the phase transition temperature of charge ordering. Analyzing the temperature dependence of the amplitude and the decay behavior of this response, the observed phenomenon is ascribed to a photo-induced transition from the low-temperature phase to a state similar to the high-temperature phase. The polarization properties indicate the produced entity is not identical with the high-temperature phase.
