Spin dynamics in IrSr2Sm1.15Ce0.85Cu2O10: Complex magnetic behavior in a layered iridocuprate

Abstract

A muon spin rotation (\ensuremath{\mu}SR), neutron, and synchrotron diffraction study of the reentrant spin-glass material IrSr${}_{2}$Sm${}_{1.15}$Ce${}_{0.85}$Cu${}_{2}$O${}_{10}$ is presented. The synthesis has been optimized, and Rietveld refinement of the diffraction patterns shows no sign of the previously reported Ir/Cu cation exchange but confirms the structure along with the disordered tilts and rotations of IrO${}_{6}$ octahedra. The zero-field-\ensuremath{\mu}SR response indicates a complex temperature dependence to the magnetism with multiple transitions that are confirmed to be bulk phenomena. Consecutive transitions are reported at ${t}_{1}$ $=$ 140, ${t}_{2}$ $=$ 20, and ${t}_{3}$ $=$ 6 K. The broad transition at 140 K is assigned to antiferromagnetic ordering of Ir${}^{4+}$ spins with a stripe spin structure. The low-temperature transitions are a result of antiferromagnetic ordering of Cu${}^{2+}$ spins followed by the freezing of a disordered Ir spin component, further evidenced by a strong damping of the oscillation amplitude below 6 K. These observations confirm the bulk nature of the previously reported reentrant spin-glass behavior of this complex magnetic system.