1/f noise in magnetite films

The low frequency electrical noise has been studied in Fe3O4 films as a fun ction of temperature and in a frequency range from 0.1 to 100 Hz. At room t emperature, Hooge's coefficient is around 80, at least three orders of magn itude greater than normally found for metals. A huge increase of the normal ized noise is observed at the Verwey transition, whose kinetics cannot be d escribed in the framework of the Dutta model. We show that the 1/f noise sc ales with the inverse of the number of carriers involved in the hopping con duction. The high noise level is analyzed in terms of slow electronic excha nges between a critical conduction network and traps or excitations widely distributed in energy near the Fermi level. (C) 1999 American Institute of Physics. [S0021-8979(99)36208-3].