Anisotropic behaviour of the magnetoresistance in single crystalline iron films

Magnetoresistive properties of single crystalline Fe(0 0 1) films with thickness in the range 5-100 nm are reported. The films possess low coercive fields (similar to 100 A/m) but a weak irreversible behaviour of the magnetization remains to fields of the order of the anisotropy field. The anisotropic behaviour of the magnetoresistance is investigated as a function of temperature and film thickness. A reversal in sign of the anisotropic magnetoresistance from negative to positive values is found at low temperatures on decreasing the film thickness from 100 to 5 nm, or by increasing the temperature from 10 to 300 K of a sufficiently thick him. The reversal in sign is associated with a crossover from Lorentz force (ordinary) to spin-orbit (extraordinary) dominated scattering processes governing the anisotropic magnetoresistance as the length scale of the electron mean free path, lambda, decreases. (C) 1999 Elsevier Science B.V. All rights reserved.