Effects of Co doping on antiferromagnetic structure in CeRhIn5

Abstract We performed the elastic neutron scattering experiments on the mixed compounds CeRh 1 - x Co x In 5 , and found that doping Co into CeRhIn 5 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 CeRhIn 5 is suppressed with increasing x , and new AF states with an incommensurate q 1 = ( 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 q 1 modulations enhanced in the intermediate Co concentrations may play a crucial role in the evolution of the superconductivity observed above x ∼ 0.4 .