Unusual Kondo behavior in the indium-rich heavy-fermion antiferromagnet Ce₃Pt₄In₁₃

We report the thermodynamic, magnetic, and electronic transport properties of the ternary intermetallic system (Ce, La)₃Pt₄In₁₃. Ce₃Pt₄In₁₃ orders antiferromagnetically at 0.95 K, while the nonmagnetic compound La₃Pt₄In₁₃ is a conventional 3.3-K superconductor. Kondo lattice effects appear to limit the entropy associated with the Néel transition to (1/4)Rln2 as an electronic contribution to the specific heat of γ∼1J/mole Ce K² is observed at T_N; roughly 35% of this γ survives the ordering transition. Hall effect, thermoelectric power, and ambient-pressure resistivity measurements confirm this interpretation. These results suggest that RKKY and Kondo interactions are closely balanced in this compound (T_N≈T_K). Contrary to expectations based on the Doniach Kondo necklace model, applied hydrostatic pressure modestly enhances the magnetic ordering temperature with dT_N/dP=+23mK/kbar. As such Ce₃Pt₄In₁₃ provides a counterexample to Kondo systems with similar Kondo and RKKY energy scales, wherein applied pressure enhances T_K at the expense of the ordered magnetic state.