Ultrafast laser induced conductive and resistive transients in La0.7Ca0.3MnO3: Charge transfer and relaxation dynamics

Pulsed laser excitation induced conductance changes in colossal magnetoresistance material La0.7Ca0.3MnO3 were studied on the picosecond time scale. A two-component signal was seen consisting of a fast positive transient associated with the paramagnetic insulating state and a slower negative signal associated with the ferromagnetic metallic state. The fast component corresponds to the photoionization of the Jahn-Teller small polaron. The slow component is explained in terms of the reduced carrier mobility due to photogenerated magnetic excitations. © 1998 The American Physical Society.