''Switching'' and re-entrant behaviour of magnetisation in ultrathin films of fcc Co upon deposition of Cu

We analyse the easy magnetisation axis ''switching'' recently discovered in experiments on Co ultrathin films with a deposited submonolayer of Cu by ab initio methods. The present large-scale calculations show that the nanomagnetic pattern of a stepped Co(001) surface 2-3 monolayers thick with submonolayer quantities of Cu has a complex three-dimensional character. We show that the maximum non-collinearity of spin-directions is about 30 , and the ''switching'' has a re-entrant character as a function of Cu coverage. (orig.)