Neutron diffraction studies on heavy fermion superconducting and antiferromagnetic compounds CeRh1–xCox In5



CeCoIn5 is a heavy fermion superconductor with the transition temperature Tc = 2.3 K, while in a related material CeRhIn5 the superconductivity is highly suppressed and an incommensurate antiferromagnetic (AFM) order characterized by the propagation vector qh = (1/2, 1/2, 0.297) appears below TN = 3.8 K. From the elastic neutron diffraction measurements on mixed compounds CeRh1–xCox In5, it was found that the superconductivity is strongly suppressed by the incommensurate AFM order while it coexists with the commensurate AFM order with qc = (1/2, 1/2, 1/2) in the intermediate x region. This is in sharp contrast to the CeRh1–xIrx In5 system, where both the commensurate and incommensurate AFM orders coexist with the superconductivity. These results reveal that particular areas on the Fermi surface nested by qh play an active role in forming the superconducting state in CeCoIn5. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)