Calculation of conductivity in the presence of structural defects: Application to spin dependence of conductivity in cobalt

We present a technique which allows the efficient calculation of the electrical conductivity of large systems which retain periodicity in only two dimensions. We use this technique to calculate the nonlocal electrical conductivity of cobalt with stacking faults. These calculations use a realistic first-principles electronic structure and evaluate the conductivity using the Kubo-Greenwood formula with a phenomenological electron lifetime. We find that the change in the electronic structure induced by the stacking faults leads to an enhancement of the spin dependence of the nonlocal electrical conductivity. A similar enhancement of the spin dependence of the conductivity is found when the crystal structure of Co is changed to hexagonal closed packed. The effect can be traced back to the shape of the Fermi surface which is almost independent of the crystal structure in the majority channel but is strongly structure dependent in the minority channel.