Long range Mn segregation and intermixing during subsequent deposition of Ge capping layers on Mn5Ge3/Ge(111) heterostructures
Résumé
We report on the Mn segregation and diffusion during the epitaxial overgrowth of Ge on Mn 5 Ge 3 /Ge(111)
heterostructures. It is shown that the underneath Mn 5 Ge 3 layers remain stabilized at the interface with the
substrate while a small amount of Mn can leave the layers and floats at the Ge growth front. Mn can then act
as a surfactant during Ge growth along the (111) orientation. The Mn segregation length and also the state of
Mn atoms incorporated in the Ge layers are found to depend on the growth temperature. At a growth
temperature of 250 °C, a segregation length of ~ 10 nm is observed and Mn atoms incorporated in the Ge
layers are uniformly distributed. At 450 °C, segregated Mn atoms can react with Ge to form Mn 5 Ge 3 clusters
inside the Ge overgrown layer. Such Mn 5 Ge 3 clusters display random orientations and induce modification of
the magnetic anisotropy of the whole film.