We have investigated the effect of Cd substitution on the archetypal heavy fermion antiferromagnet CeIn3 via magnetic susceptibility, specific-heat, and resistivity measurements. The suppression of the Neel temperature, TN, with Cd doping is more pronounced than with Sn. Nevertheless, a doping-induced quantum critical point does not appear to be achievable in this system. The magnetic entropy at TN and the temperature of the maximum in resistivity are also systematically suppressed with Cd, while the effective moment and the Curie-Weiss temperature in the paramagnetic state are not affected. These results suggest that Cd locally disrupts the antiferromagnetic order on its neighboring Ce moments, without affecting the valence of Ce. Moreover, the temperature dependence of the specific heat below TN is not consistent with three-dimensional magnons in pure as well as in Cd-doped CeIn3, a point that has been missed in previous investigations of CeIn3 and that has bearing on the type of quantum criticality in this system. © 2010 The American Physical Society.

Heat capacity, resistivity, and magnetic susceptibility measurements confirm bulk superconductivity in single crystals of BaIr2 P2 (Tc =2.1K) and BaRh2 P2 (Tc =1.0K). These compounds form in the ThCr2 Si2 (122) structure so they are isostructural to both the Ni and Fe pnictides but not isoelectronic to either of them. This illustrates the importance of structure for the occurrence of superconductivity in the 122 pnictides. Additionally, a comparison between these and other ternary phosphide superconductors suggests that the lack of interlayer P-P bonding favors superconductivity. These stoichiometric and ambient pressure superconductors offer an ideal playground to investigate the role of structure for the mechanism of superconductivity in the absence of magnetism. © 2009 The American Physical Society.

We report on de Haas-van Alphen (dHvA) and band-structure studies of the iridium-pnictide superconductor BaIr2P2 (Tc=2.1 K). The observed dHvA frequencies can be well understood by our band-structure calculations with two bands crossing the Fermi energy leading to a strongly corrugated Fermi-surface cylinder around the X point and a highly evolved, multiconnected Fermi surface extending over the whole Brillouin zone. The experimental effective masses are found to be considerably larger than the calculated band masses suggesting strong many-body interactions. Nevertheless, Tc remains only moderate in BaIr2P2 contrary to isostructural iron pnictides which probably is related to the largely different Fermi-surface topologies in these materials.