Structure and Magnetism of (La/Sr)MIrO and Topochemically Reduced (La/Sr)MIrO (M = Fe, Co) Complex Oxides.

Neutron powder diffraction data show that SrFeIrO, SrCoIrO, and LaSrCoIrO all adopt undistorted, n = 1 Ruddlesden-Popper structures in which the Ir and Fe/Co/Co cations are statistically disordered over all the octahedral coordination sites. Magnetization data indicate the two cobalt phases are spin glasses at low temperature, while SrFeIrO appears to adopt an antiferromagnetic state with very small magnetically ordered domains. Topochemical reduction with a Zr getter converts the tetragonal AMIrO phases to the corresponding orthorhombic AMIrO phases in which the Ir and Fe/Co/Co cations are located in approximately square-planar coordination sites. Magnetization data indicate SrFeIrO is a spin glass below T ∼ 30 K, while SrCoIrO appears to be antiferromagnetic below T ∼ 25 K and LaSrCoIrO shows no sign of magnetic order for T > 5 K. The magnetic behavior of both the AMIrO and AMIrO phases is discussed on the basis of metal d-electron count and structural features.