Effective medium-range Mn–Mn pair interaction induces pseudogap in the density of states of Al(Si)–Mn approximants

The effect on the electronic structure of an effective medium-range Mn–Mn interaction mediated by the valence states and the sp–d hybridization is presented. In Al(rich)–Mn phases related to quasicrystals (Al12Mn, o-Al6Mn, α-Al9Mn2Si), this effective interaction creates a Hume-Rothery pseudogap in the density of states together with a minimization of the band energy. It is shown that the Mn–Mn interaction up to the distance around 10–20 Å plays an essential role in stabilizing related quasicrystal structures.