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Spin ordering in the mixed-ligand antiferromagnet Mn(dca)2(pyrazine)

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The flexibility offered by molecular-based systems allows us to introduce or replace specific ligands in a material with the aim of radically altering desired structural and magnetic properties. Specifically, Mn(dca)2(pyz) {dca = dicyanamide, [N(CN)2]-; pyz = pyrazine} has a unique interpenetrating ReO3-like lattice. The Mn2+ cations are high-spin (S = 5/2) and the material orders antiferromagnetically below TN = 2.53(2) K. Using neutron powder diffraction we observed a collinear spin structure oriented along the short ac-diagonal of the monoclinic unit cell. Inelastic neutron scattering results show a magnetic excitation at 0.23 meV. The strong dispersion character of this excitation demonstrates that it is related to a low-energy spin wave. Upon warming, the magnon gradually softens and disappears at TN, while critical scattering becomes evident by a broad quasielastic response above TN. The energy of the magnon is consistent with the exchange parameter, J, derived from magnetic susceptibility measurements.

TidsskriftJournal of Magnetism and Magnetic Materials
Udgave nummer3
Sider (fra-til)462-466
Antal sider5
StatusUdgivet - 1 apr. 2003
Eksternt udgivetJa

ID: 210118343