Electrical noise from phase separation in Pr2/3Ca1/3MnO3 single crystal

Low frequency electrical noise measurements have been used to probe the ele ctronic state of the perovskite-type manganese oxide Pr2/3Ca1/3MnO3 versus temperature and in the vicinity of the field-induced transition from the in sulating, charge-ordered (I-CO) state to the metallic, ferromagnetic state (M-F). At high temperature we have observed a high level of the excess nois e with mainly a Gaussian distribution of the resistance fluctuations, and t he associated power spectral density has a standard 1/f dependence. However , in the hysteretic region, where the electrical resistance depends dramati cally on the sample history, we have observed a huge non-Gaussian noise cha racterized by two level fluctuator-like switching in the time domain. We di scuss the origin of the noise in terms of percolative behavior of the condu ctivity. We speculate that the dominant fluctuators are manganese clusters switching between the M-F and the I-CO phases. (C) 2000 American Institute of Physics. [S0021-8979(00)53908-5].