Magnetic transition inMnn(n=2–8)clusters

Abstract

Theoretical electronic structure studies on ${\mathrm{Mn}}_{n}$ $(n=2--8)$ clusters have been carried out using a linear-combination-of-atomic-orbitals--molecular-orbital approach within the density-functional formalism. It is shown that ${\mathrm{Mn}}_{2}$ and ${\mathrm{Mn}}_{3}$ have energetically close ferromagnetic and antiferromagnetic or frustrated antiferromagnetic solutions. ${\mathrm{Mn}}_{4},$ ${\mathrm{Mn}}_{5},$ ${\mathrm{Mn}}_{6},$ ${\mathrm{Mn}}_{7},$ and ${\mathrm{Mn}}_{8}$ are all ferromagnetic with moments of 20, 23, 26, 29, and 32${\ensuremath{\mu}}_{B}.$ The appearance of ferromagnetic character is shown to be accompanied by bonding between minority d states. The relation between geometry and multiplicity and the possibility of closely spaced multiplet states are discussed.