Magnetic and transport properties of lanthanide rhenates Ln4Re6O19 (Ln = La,Pr,Nd)

The crystal structures and magnetic properties of Ln4Re6O19 (Ln = La,Pr,Nd) are reported. They crystallize in a cubic structure with space group I 23 and have a three-dimensional network of Re2O10 dimers consisting of two edge-sharing ReO6 octahedra. Measurements of the magnetic susceptibility, specific heat, and electrical resistivity for Ln4Re6O19 and the calculation of the electronic structure for La4Re6O19 reveal that the 5d electrons of the Re ion are delocalized and that these compounds are metallic. For Ln4Re6O19 (Ln = Pr,Nd), a Schottky-type specific heat anomaly is observed at 2 K for Ln = Pr and 5 K for Ln = Nd, which is due to the short-range magnetic orderings in the Ln4O tetrahedral cluster. Furthermore, for the Nd4Re6O19 compound, the long-range magnetic ordering via conduction electrons is found at 0.45 K.

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