Effects of Co doping on antiferromagnetic structure in CeRhIn5

We performed the elastic neutron scattering experiments on the mixed compounds CeRh1-xCoxIn5, and found that doping Co into CeRhIn5 dramatically changes the antiferromagnetic (AF) structure. The incommensurate AF state with the propagation vector of qh=(12,12,∼0.3) observed in pure CeRhIn5 is suppressed with increasing x, and new AF states with an incommensurate q1=(12,12,∼0.4) and a commensurate qc=(12,12,12) modulations simultaneously develop near the AF quantum critical point: xc∼0.8. These results suggest that the AF correlations with the qc and q1 modulations enhanced in the intermediate Co concentrations may play a crucial role in the evolution of the superconductivity observed above x∼0.4.