Overlayers, interlayers, and surface alloys of Mn on the Cu(111) surface

The energetics of various surface alloys of manganese on copper (111) are calculated and their stability against clustering and/or interdiffusion is determined by an ab initio method. The interplay between stoichiometry, chemical, and magnetic ordering allows for a large variety of ordered alloys; only two are found to be stable against clustering: a 33% alloy and a 50% alloy of antiferromagnetically ordered Mn chains. Thermodynamic considerations indicate that only the 33% alloy will be formed at temperatures typical for epitaxial growth. The results;are compared to recent scanning tunneling microscopy experiments.