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

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