Abstract
We report magnetic studies on nickel nanoparticle films of average particle size of 10
nm. Magnetization as a function of field and temperature show that the system behaves like a random magnet with a strongly field-dependent irreversible temperature, below which the magnetization relax logarithmically with time. The effective barrier extrapolated increases strongly with temperature for a given field. The time dependence suggests the dominant dipole–dipole interaction in this magnetic nanoparticle system.
