  We have performed magnetoresistance measurements on single-domain, submicron
elliptical Ni particles using nonmagnetic probes in a four probe geometry at
liquid helium temperatures. In the smallest particles, the magnetoresistance
shows sharp jumps which are associated with the switching of individual
domains. Using an anisotropic magnetoresistance model, we can reconstruct
hysteresis loops of the normalized magnetization. The remanent magnetization in
zero applied magnetic field is typically 15 percent less than the saturation
magnetization. This relaxation of the magnetization may be due to surface
effects or crystal grain structure in the particles.
