A new class of ferromagnetic semiconductor: Copper molybdate organic-inorganic compound with phenanthroline organic linkers

Abstract

A three-dimensional (3D) framework of covalently-bonded layers of bimetallic inorganic oxide, CuMoO4, interlinked by electron-rich organic ligands, which is semiconducting and also ferromagnetic, has been prepared. The structure [Cu(3,8-phenanthroline)(0.5)MoO4] consists of molybdate tetrahedra corner-shared with clusters of edge-sharing {CuO5N} octahedra. The injection of charge carriers into the inorganic layers by phenanthroline induces different magnetic orderings at different temperatures, orderings which are not found in the structurallysimilar [Cu(4,4'-bipyridine)(0.5)MoO4]. The temperature dependence of the susceptibility shows two low temperature magnetic transitions: weakly ferromagnetic-coupled spins below 15 K coexisting with an anti-ferromagnetic structure below 10 K. Specific heat capacity shows a finite ground-state electronic specific heat coefficient, gamma = 0.094 J/mol.K-2, that is higher than that of the bipyridine counterpart (0.068 J/mol.K-2), confirming an increase in the electronic density-of-states in the phenanthroline system.