Structure-property relations in the distorted ordered double perovskite Sr2InReO6

Abstract

The rock-salt ordered type double perovskite Sr${}_{2}$InReO${}_{6}$ 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 Sr${}_{2}$InReO${}_{6}$ is revised to be monoclinic (cryolite structure type, space group $P$2${}_{1}$/$n$) with all structural distortions according to the high-symmetry aristotype due to tilting of the InO${}_{6}$ and ReO${}_{6}$ octahedra, respectively. Sr${}_{2}$InReO${}_{6}$ is a Mott insulator with variable-range hopping. Two 5$d$ electrons are unpaired and localized on the Re${}^{5+}$ ions. Although there are antiferromagnetic interactions, the fcc arrangement of the Re${}^{5+}$ cations (5${d}^{2}$) 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.