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 e lectrical conductivity of large systems which retain periodicity in on ly two dimensions. We use this technique to calculate the nonlocal ele ctrical conductivity of cobalt with stacking faults. These calculation s use a realistic first-principles electronic structure and evaluate t he conductivity using the Kubo-Greenwood formula with a phenomenologic al electron lifetime. We find that the change in the electronic struct ure induced by the stacking faults leads to an enhancement of the spin dependence of the nonlocal electrical conductivity. A similar enhance ment of the spin dependence of the conductivity is found when the crys tal 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 i ndependent of the crystal structure in the majority channel but is str ongly structure dependent in the minority channel.