The de Haas-Van Alphen Effect in CeMIn5 (where M = rh and Co)

To understand the electronic structure of the heavy fermion superconductors CeMIn₅, we have performed a comprehensive magnetic study of these materials.^1-4 Our quantum oscillation studies reveal that the Fermi surface becomes systematically more 2-d (and displays heavier effective masses) as one progresses from M=Rh to M=Ir to M=Co, consistent with the observed increase in superconducting T_c. Furthermore, dilution studies show that the f-electrons in CeRhIn₅ are substantially localized whereas in CeIrIn₅ and CeCoIn₅ a more itinerant character is observed.