Thermal and magnetic properties of the low-temperature antiferromagnet Ce4 Pt12 Sn25
Abstract
We report specific heat (C) and magnetization (M) of single crystalline Ce4 Pt12 Sn25 at temperature down to ∼50 mK and in fields up to 3 T. C/T exhibits a sharp anomaly at 180 mK, with a large ΔC/T∼30 J/molCe K2, which, together with the corresponding cusplike magnetization anomaly, indicates an antiferromagnetic (AFM) ground state with a Néel temperature TN =180 mK. Numerical calculations based on a Heisenberg model reproduce both zero-field C and M data, thus placing Ce 4 Pt12 Sn25 in the weak exchange coupling J< Jc limit of the Doniach diagram, with a very small Kondo scale TK TN. Magnetic field suppresses the AFM state at H⊃ ≈0.7 T, much more effectively than expected from the Heisenberg model, indicating additional effects possibly due to frustration or residual Kondo screening. © 2010 The American Physical Society.
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