Effects of Co doping on antiferromagnetic structure in CeRhIn5

We performed the elastic neutron scattering experiments on the mixed compounds CeRh_1-xCo_xIn₅, and found that doping Co into CeRhIn₅ dramatically changes the antiferromagnetic (AF) structure. The incommensurate AF state with the propagation vector of q_h=({1}/{2},{1}/{2},∼0.3) observed in pure CeRhIn₅ is suppressed with increasing x, and new AF states with an incommensurate q₁=({1}/{2},{1}/{2},∼0.4) and a commensurate q_c=({1}/{2},{1}/{2},{1}/{2}) modulations simultaneously develop near the AF quantum critical point: x_c∼0.8. These results suggest that the AF correlations with the q_c 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.