Nonlinear electrical conduction and broad band noise in the charge-orderedrare earth manganate Nd0.5Ca0.5MnO3

Measurements of the dc transport properties and the low-frequency conductiv ity noise in films of charge-ordered Nd0.5Ca0.5MnO3 grown on Si substrate r eveal the existence of a threshold field in the charge-ordered regime beyon d which strong nonlinear conduction sets in along with a large broad band c onductivity noise. Threshold-dependent conduction disappears as T --> T-CO, the charge-ordering temperature. This observation suggests that the charge -ordered state gets depinned at the onset of the nonlinear conduction. (C) 1999 American Institute of Physics. [S0003-6951(99)05247-X].