μSR study of the effects of Ce dilution on the development of the heavy-fermion state in (Ce,La)2IrIn8

We have performed muon Knight shift measurements in the heavy-fermion compound (Ce1-xLax)2IrIn8, x=0.1, in 1 T magnetic field applied along the crystalline c-axis. Although the Knight shift K scales linearly with susceptibility χ above T∼20K, a breakdown of this relationship was observed below a temperature T*=20.1(8)K. It was found that this Knight shift anomaly occurs due to a low-temperature susceptibility component χcf∼(1-T/T*)ln(T*/T), corresponding to the formation of a coherent heavy-fermion state below T*, as found previously in the x=0 compound. The characteristic temperature T* is reduced by about 4 K for 10% La doping, indicating a reduction in the strength of the intersite Ce fluctuations associated with the heavy electron state.