Thermal and magnetic properties of a low-temperature antiferromagnet Ce${}_4$Pt${}_{12}$Sn${}_{25}$

Abstract

We report specific heat ($C$) and magnetization ($M$) of single crystalline Ce${}_4$Pt${}_{12}$Sn${}_{25}$ at temperature down to $\sim$50mK and in fields up to 3T. $C/T$ exhibits a sharp anomaly at 180mK, with a large $\hat{I}”C/T\sim$30J/molK${}^2$-Ce, which, together with the corresponding cusp-like magnetization anomaly, indicates an antiferromagnetic (AFM) ground state with a Néel temperature $T_N$=180mK. Numerical calculations based on a Heisenberg model reproduce both zero-field $C$ and $M$ data, thus placing Ce${}_4$Pt${}_{12}$Sn${}_{25}$ in the weak exchange coupling $J<J_c$ limit of the Doniach diagram, with a very small Kondo scale $T_K\ll T_N$. Magnetic field suppresses the AFM state at $H^{\ast }\approx$0.7T, much more effectively than expected from the Heisenberg model, indicating additional effects possibly due to frustration or residual Kondo screening.

8 pages, 7 figures, accepted for publication in Phys. Rev. B