Magnetic Properties of Polar ZnO Surfaces from Ab-initio Calculations

We have studied the effect that applying self-interaction correction (SIC) to oxygen p orbitals has on the magnetic moment formation of three polar ZnO surfaces; all of them being oxygen terminated. For these investigations we have used a multi-code approach. This has allowed us, on the one hand, to relax the surface structure using the pseudopotential code SIESTA. On the other hand, by using the obtained relaxed structures for calculations within the KKR Green’s function formalism, we have been able to apply SIC and use the magnetic force theorem for calculating Heisenberg exchange parameters. The latter contain information about both the strength of the interaction and the interaction mechanism. Our calculations show that all three surfaces are magnetic. In addition, we find that applying SIC is necessary to correctly describe the top oxygen atom of the (0001)-t and (0001)-h surfaces.