Structure-property relations in the distorted ordered double perovskite Sr2InReO6

The rock-salt ordered type double perovskite Sr2InReO6 is systematically investigated by means of powder x-ray diffraction, neutron powder diffraction, temperature-dependent electrical transport, heat capacity and magnetic susceptibility measurements, and electronic band structure calculations. The crystal structure of Sr2InReO6 is revised to be monoclinic (cryolite structure type, space group P2(1)/n) with all structural distortions according to the high-symmetry aristotype due to tilting of the InO6 and ReO6 octahedra, respectively. Sr2InReO6 is a Mott insulator with variable-range hopping. Two 5d electrons are unpaired and localized on the Re5+ ions. Although there are antiferromagnetic interactions, the fcc arrangement of the Re5+ cations (5d(2)) leads to a geometrically frustrated spin system that does not achieve full magnetic order. The experimental findings are in line with the results of electronic structure computation using the WIEN2K program within the GGA + U approximation exclusively on the basis of the revised crystal structure model.