LAUSR

Abstract Magnetization, electron spin resonance (ESR) spectra and resistivity measurements have been performed on the doped pyrochlore iridate Y2Ir2−xFexO7. Magnetization data show the onset of magnetic irreversibility changes little with gradual substitution of Fe. Both the bulk magnetism and the micromagnetism demonstrate that the system becomes less antiferromagnetic (AFM) as more Ir4+ ions are substituted by Fe3+ ions, which is due to the appearance of ferromagnetic (FM) Fe interactions and broken networks of Ir ions. Both the macromagnetism parameters (Curie-Weiss temperature and effective magnetic moment) and micromagnetism parameters (effective g factor, peak-to-peak intensity Ipp, and peak-to-peak width ΔHpp) present nonmonotonic evolution with doping, suggesting coexistence of FM and AFM interactions. Ir ions have mixed valence of Ir4+ and Ir3+ and Fe3+ ions are in high-spin state in doped samples. The resistivity data show that all the compounds are insulators and follow an inverse power law ρ = ρ0T−n well in the whole temperature range. The complex variation of resistivity and magnetism should be a consequence of variation of both SOC and U, as well as hole doping.