Probing the ground state magnetism at the local scale of an unusual metallic pyrochlore Pb2-xCdxIr2O7-d;

Common d5 pyrochlore iridates, A2Ir2O7 or A2Ir2O6O’, are reported to have long range magnetic order based on muSR experiment. Only Pr2Ir2O7 has been identified as a metallic spin liquid. The lone d4 pyrochlore Pb2Ir2O7-d; appears different due to nonmagnetic Pb at A-site and high vacancy tolerance at O’ site due to Pb 6s2 lone pair. This large oxygen vacancy ensures presence of Ir4+ and Ir5+, but the susceptibility shows a paramagnet-like trend with negative theta. Moreover, the system shows a non-T2-type metallic resistivity. To tune the Ir4+ and Ir5+ ratio by controlling the vacancy content, lower sized Cd cation is doped at the Pb site (Pb2-xCdxIr2O7-d; with x=0, 0.5, 0.8) which reduces moment by increasing Ir5+ (J=0) content but the susceptibility remained similar. Hence the local magnetic structure in Pb2Ir2O7-d; and its evolution with Cd-doping will be worth investigating by muSR.