Structure, magnetism and electronic properties in 3d-5d based double perovskite ([Formula: see text]Y _x )₂FeIrO₆

The 3d-5d based double perovskites are of current interest as they provide model systems to study the interplay between electronic correlation (U) and spin-orbit coupling (SOC). Here, we report detailed structural, magnetic and transport properties of doped double perovskite material ([Formula: see text]Y _x )₂FeIrO₆ with [Formula: see text]. With substitution of Y, the system retains its original crystal structure but structural parameters change with x in nonmonotonic fashion. The magnetization data for Sr₂FeIrO₆ show antiferromagnetic type magnetic transition around 45 K; however, a close inspection of the data indicates a weak magnetic phase transition around 120 K. No change of structural symmetry has been observed down to low temperature, although the lattice parameters show sudden changes around the magnetic transitions. Sr₂FeIrO₆ shows an insulating behavior over the whole temperature range, which nevertheless does not change with Y substitution. The nature of charge conduction is found to follow thermally activated Mott's variable range hopping and power law behavior for parent and doped samples, respectively. Interestingly, evolution of structural, magnetic and transport behavior in ([Formula: see text]Y _x )₂FeIrO₆ is observed to reverse with [Formula: see text], which is believed to arise due to a change in the transition metal ionic state.