Magnetic transition inMnn(n=2–8)clusters

Abstract

Theoretical electronic structure studies on Mn n (nϭ2 -8) clusters have been carried out using a linearcombination-of-atomic-orbitals-molecular-orbital approach within the density-functional formalism. It is shown that Mn 2 and Mn 3 have energetically close ferromagnetic and antiferromagnetic or frustrated antiferromagnetic solutions. Mn 4 , Mn 5 , Mn 6 , Mn 7 , and Mn 8 are all ferromagnetic with moments of 20, 23, 26, 29, and 32 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.

Magnetic structure variation in manganese-oxide clusters

“…[1][2][3][4][5][6][7][8] The magnetic ordering of the Mn 2 dimer is very sensitive to interatomic separation, [1][2][3] while clusters containing 3-5 Mn atoms are all predicted to have ferromagnetic ground states with magnetic moments of ∼5 μ B /atom. 2,4,5 Mn 6 and Mn 7 are ferrimagnetic, 5,9 and there is a distinct transition from high-to low-spin configurations in Mn n clusters with n ≥ 7. 5 In all anionic clusters, Mn − n (n = 2-8), the preferred ordering is ferromagnetic.…”

“…11 They found that the ferromagnetic states of Mn 5 and Mn 6 are destabilized by the addition of oxygen, and the overall magnetic moment is reduced compared to pure Mn n clusters. Another conclusion of this work was the identification of several nearly degenerate "isomags."…”

“…Mn 5 O and Mn 6 O were studied by Jones et al using a combination of negative-ion PES and quantum calculations. 11 They found that the ferromagnetic states of Mn 5 and Mn 6 are destabilized by the addition of oxygen, and the overall magnetic moment is reduced compared to pure Mn n clusters.…”

Anomalous Magnetic Moments of Mn<SUB><B>13</B></SUB> and Mn<SUB><B>19</B></SUB> Clusters

“…1,2) The 3d 5 4s 2 atomic electronic configuration makes Mn 2 very weakly bonded with van der Waals interaction and the nature of the magnetic coupling in the dimer is still disputed. In bulk, manganese has the lowest cohesive energy (2.92 eV/atom) and large compressibility among the 3d metals.…”

“…1,2) Recent experiments on Mn clusters with 11-99 atoms show magnetically ordered clusters with significantly reduced moments and a maximum value of about 1.4 µ B /atom. 3) This is close to the magnetic moments of about 1 µ B in bulk Mn.…”