Magnetic map of Mn-based thin films on Ni/Cu

摘要

Ab initio density-functional theory in generalized gradient approximation is used to perform calculations on the magnetic structure of Mn thin films and Mn-Ni ordered surface alloys on Ni/Cu. For the Mn monolayer on Ni(001), Ni(011), and Ni(111), we found that the ground state corresponds to an antiferromagnetic coupling between Mn atoms. Ni subsurface atoms adjacent to Mn surface display two different values (0.26μ_B and 0.13μ_B) of the magnetic moment in the (111) crystallographic face. For the ordered Mn_(0.5)Ni_(0.5) monolayer on Ni a ferromagnetic configuration has been obtained. At variance, for the ordered Mn_(0.5)Ni_(0.5) two-layers thick on Ni an antiferromagnetic coupling between Mn atom nearest-neighboring positions are depicted for the (001) and (011) crystallographic faces whereas it is ferromagnetic for (111) one. Ni magnetic moments at surface alloy are killed (-0.04μ_B). Mn overlayer and 1-2 ML surface alloy always present a large rippling, in qualitative agreement with experimental measurements [M. Wuttig and C. C. Knight, Phys. Rev. B 48, 12130 (1993); M. De Santis, V. Abad-Langlais, Y. Gautier, and P. Dolle, Phys. Rev. B 69, 115430 (2004)].