Time dependence of GMR in granular alloys

We have studied time dependent effects in NiFeAg granular alloy films at low temperatures. Measurements of the time dependence of magnetisation and resistivity have been made at 5 K. We have observed large time dependent changes in the magnetisation but much smaller changes in the resistivity at similar applied fields. The time dependence of magnetisation exhibits a peak in the magnetic viscosity at fields near to the coercivity whereas the resistivity time dependence is much smaller. We interpret this effect in terms of a simple approach relating the resistivity to M/sup 2/.