Negative magnetoresistance produced by Hall fluctuations in a ferromagnetic domain structure

We present a model for a negative magnetoresistance (MR) that would develop in a material with many ferromagnetic domains even if the individual domai ns have no magnetoresistance and even if there is no boundary resistance. T he negative MR is due to a classical current-distortion effect arising from spatial variations in the Hall conductivity, combined with a change in dom ain structure due to an applied magnetic field. The negative MR can exceed 1000% if the product of the carrier relaxation time and the internal magnet ic field due to spontaneous magnetization is sufficiently large. (C) 2001 A merican Institute of Physics.