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Magnetic measurements and neutron diffraction study of the layered hybrid compounds Mn(C8H4O4)(H2O)2 and Mn2(OH)2(C8H4O4)

2011; Elsevier BV; Volume: 186; Linguagem: Inglês

10.1016/j.jssc.2011.12.009

1095-726X

Romain Sibille, Adel Mesbah, Thomas Mazet, B. Malaman, Silvia C. Capelli, Michel François,

Organic and Molecular Conductors Research

Mn(C8H4O4)(H2O)2 and Mn2(OH)2(C8H4O4) layered organic–inorganic compounds based on manganese(II) and terephthalate molecules (C8H4O42−) have been studied by DC and AC magnetic measurements and powder neutron diffraction. The dihydrated compound behaves as a 3D antiferromagnet below 6.5 K. The temperature dependence of its χT product is typical of a 2D Heisenberg system and allows determining the in-plane exchange constant J≈−7.4 K through the carboxylate bridges. The magnetic structure confirms the in-plane nearest neighbor antiferromagnetic interactions and the 3D ordering. The hydroxide based compound also orders as a 3D antiferromagnet with a higher Néel temperature (38.5 K). Its magnetic structure is described from two antiferromagnetically coupled ferromagnetic sublattices, in relation with the two independent metallic sites. The isothermal magnetization data at 2 K are consistent with the antiferromagnetic ground-state of these compounds. However, in both cases, a slope change points to field-induced modification of the magnetic structure.