3 research outputs found
High pressure phase diagrams of CeRhIn and CeCoIn studied by ac calorimetry
The pressure-temperature phase diagrams of the heavy fermion antiferromagnet
CeRhIn and the heavy fermion superconductor CeCoIn have been studied
under hydrostatic pressure by ac calorimetry and ac susceptibility measurements
using diamond anvil cells with argon as pressure medium. In CeRhIn, the use
of a highly hydrostatic pressure transmitting medium allows for a clean
simultaneous determination by a bulk probe of the antiferromagnetic and
superconducting transitions. We compare our new phase diagram with the previous
ones, discuss the nature (first or second order) of the various lines, and the
coexistence of antiferromagnetic order and superconductivity. The link between
the collaps of the superconducting heat anomaly and the broadening of the
antiferromagnetic transition points to an inhomogeneous appearence of
superconductivity below GPa. Homogeneous bulk
superconductivity is only observed above this critical pressure. We present a
detailed analysis of the influence of pressure inomogeneities on the specific
heat anomalies which emphasizes that the observed broadening of the transitions
near is connected with the first order transition. For CeCoIn we show
that the large specific heat anomaly observed at at ambient pressure is
suppressed linearly at least up to 3 GPa
Heat capacity studies of Ce and Rh site substitution in the heavy fermion antiferromagnet CeRhIn_5;: Short-range magnetic interactions and non-Fermi-liquid behavior
In heavy fermion materials superconductivity tends to appear when long range
magnetic order is suppressed by chemical doping or applying pressure. Here we
report heat capacity measurements on diluted alloyes of the heavy fermion
superconductor CeRhIn_5;. Heat capacity measurements have been performed on
CeRh_{1-y}Ir_{y}In_5; (y <= 0.10) and Ce_{1-x}La_{x}Rh_{1-y}Ir_{y}In_5; (x <=
0.50) in applied fields up to 90 kOe to study the affect of doping and magnetic
field on the magnetic ground state. The magnetic phase diagram of
CeRh_{0.9}Ir_{0.1}In_5; is consistent with the magnetic structure of CeRhIn_5;
being unchanged by Ir doping. Doping of Ir in small concentrations is shown to
slightly increase the antiferromagnetic transition temperature T_{N} (T_{N}=3.8
K in the undoped sample). La doping which causes disorder on the Ce sublattice
is shown to lower T_{N} with no long range order observed above 0.34 K for
Ce_{0.50}La_{0.50}RhIn_5;. Measurements on Ce_{0.50}La_{0.50}RhIn_5; show a
coexistence of short range magnetic order and non-Fermi-liquid behavior. This
dual nature of the Ce 4f-electrons is very similar to the observed results on
CeRhIn_5; when long range magnetic order is suppressed at high pressure.Comment: 8 pages, 9 figure