Magic monatomic linear chains for Mn nanowire self-assembly on Si(001)

Using first-principles calculations, we unveil an atomistic nucleation process of monoatomic Mn nanowire self-assembly on Si(001). We find that Mn adatoms form magic 3n+1 atom dense trimerlike linear chains (DTLCs) driven by pedestal site adsorption. Moreover, the length of DTLCs is limited by a competing process to form three-dimensional D3h-Mn5 clusters in early stages. These results establish a new structural model distinct from the dimerlike linear chains for III and IV group elements on Si(001) and provide a natural explanation for recent experimental observations.