Photoinduced Insulator-to-Metal Transition in a Perovskite Manganite

We have observed an insulator-to-metal (I-M) transition triggered by the photocarrier injection into the charge-ordered (CO) state of a perovskite manganite crystal, Pr0.7Ca 0.3MnO 3. The photocurrent is a highly nonlinear function of applied electric field and of light intensity; both show a threshold behavior for the I-M transition. The dependence of the anomalous photocurrent on the excitation photon energy and the temperature excludes the laser heating as the cause of the effect, suggesting the photocarrier-mediated collapse of the CO state. copyright 1997 The American Physical Society