Magnetic interactions in epitaxial films of Mn5(Ge1-xSix)3/Ge(111) 5 (Ge 1-x Si x ) 3 /Ge(111): 55 Mn NMR study

55 Mn NMR experiments have been performed at 4.2 K on a series of Mn5(Ge1-xSix)3 5 (Ge 1- x Si x ) 3 epitaxial films (0 0 x 0.55) . 55 ) to investigate changes introduced by silicon when it replaces germanium in a hexagonal Mn5Ge3 5 Ge 3 crystal lattice. The Si/Ge substitution was found to reduce the magnetic moment on manganese located in the 6(g) sublattice creating a new population of manganese atoms with distinctly lower magnetic moment. This effect is attributed to the orbital overlay due to a lattice distortion introduced by Si. Interestingly, these modified Mn sites retain the orbital moment practically unaltered. The amount of new manganese environments in the 6(g) sublattice coincides with a probability of Mn having two Si neighbors as first neighbors. Mn atoms located in the 4(d) sublattice are not significantly affected by the Si substitution in the studied concentration range.