Interplay between magnetism and superconductivity in CeMIn5 heavy fermion

Abstract We report a single-crystal magnetic neutron diffraction study on the antiferromagnetic and superconducting heavy-fermion compound CeRh 0.65 Ir 0.35 In 5 . Our experiments detect no change in the magnetic structure on cooling the single crystals below T C indicating the coexistence of long-range magnetic order and superconductivity. We also show that an applied magnetic field converts the magnetic structure from incommensurate to commensurate. This work places new constraints on interpretations of the relationship between antiferromagnetism and unconventional superconductivity in this family of heavy-fermion superconductors.