Magnetic interactions in rhenium-containing rare earth double perovskites Sr2LnReO6 (Ln=rare earths)

The perovskite-type compounds containing both rare earth and rhenium Sr(2)LnReO(6) (Ln=Y, Tb-Lu) have been prepared. Powder X-ray diffraction measurements and Rietveld analysis show that Ln(3+) and Re5+ ions are structurally ordered at the B site of the perovskite SrBO3. Magnetic anomalies are found in their magnetic susceptibility and specific heat measurements at 2.6-20 K for Ln=Y, Tb, Dy, Yb, Lu compounds. They are due to magnetic interactions between Re5+ ions. The results of the magnetic hysteresis and remnant magnetization measurements for Sr2YReO6 and Sr2LuReO6 indicate that the antiferromagnetic interactions between Re5+ ions below transition temperatures have a weak ferromagnetic component. The analysis of the magnetic specific heat data for Sr2YbReO6 shows that both the Yb3+ and Re5+ ions magnetically order at 20 K. For the case of Sr2DyReO6, magnetic ordering of the Re5+ moments occurs at 93 K, and with decreasing temperature, the moments of Dy3+ ferromagnetically order at 5 K from the measurements of magnetic susceptibility and specific heat.