Neutron diffraction studies on heavy fermion superconducting and antiferromagnetic compounds CeRh1-xCoxIn5

CeCoIn5 is a heavy fermion superconductor with the transition temperature T-c = 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 q(h) = (1/2, 1/2, 0.297) appears below T-N = 3.8 K. From the elastic neutron diffraction measurements on mixed compounds CeRh1-xCoxIn5, it was found that the superconductivity is strongly suppressed by the in-commensurate AFM order while it coexists with the commensurate AFM order with q(c) = (1/2, 1/2, 1/2) in the intermediate x region. This is in sharp contrast to the CeRh1-xIrxIn5 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 q(h) play an active role in forming the superconducting state in CeCoIn5. (c) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim