Giant magnetoresistance in quantum magnetic contacts

We present calculations of quantized conductance and magnetoresistance in nanosize point contacts between two ferromagnetic metals. When conductance is open for only one conduction electron spin-projection, the magnitude of magnetoresistance is limited by the rate of conduction electron spin-reversal processes. In the case when both spin-channels contribute to the conductance we analyze the influence of the point contact cross-section asymmetry on the giant megnetoresistance. Recent experiments on magnetoresistance of magnetic point contacts are discussed in the framework of the developed theory. © 2002 Elsevier Science B.V. All rights reserved