Quantized conductance and giant MR effect in atomic-sized ferromagnetic contacts

In this paper we investigate the origin of the giant magnetoresistance effect in atomic-sized magnetic contacts within the framework of Landauerʹs theory, which relates scattering to conductance in a direct way. It is believed that in magnetic contacts the scattering mechanism is spin-dependent, provided by the exchange interaction between local spin and itinerant electrons. In our model the local spin distribution is explained in terms of localized d-electrons obeying a Heisenberg Hamiltonian while the electronic transport is taken into account by itinerant s-like electrons according to the Anderson model. As the main result we show that the MR effect is strongly dependent on spin-flipping probability of conduction electrons.