1 / f noise in magnetite films

The low frequency electrical noise has been studied in [formula omitted] films as a function of temperature and in a frequency range from 0.1 to 100 Hz. At room temperature, Hooge's coefficient is around 80, at least three orders of magnitude greater than normally found for metals. A huge increase of the normalized noise is observed at the Verwey transition, whose kinetics cannot be described in the framework of the Dutta model. We show that the [formula omitted] noise scales with the inverse of the number of carriers involved in the hopping conduction. The high noise level is analyzed in terms of slow electronic exchanges between a critical conduction network and traps or excitations widely distributed in energy near the Fermi level. © 1999, American Institute of Physics. All rights reserved.