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

TL;DR

This study investigates the low-temperature antiferromagnetic behavior of Ce$_4$Pt$_{12}$Sn$_{25}$ through specific heat and magnetization measurements, revealing a Néel temperature of 180mK and effects of magnetic field suppression.

Contribution

The paper provides the first detailed thermodynamic and magnetic characterization of Ce$_4$Pt$_{12}$Sn$_{25}$, including numerical modeling that places it within the weak exchange coupling regime.

Findings

Identifies antiferromagnetic order at 180mK.

Shows magnetic field suppresses AFM state at ~0.7T.

Numerical models match experimental data, indicating weak exchange coupling.

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 $\Delta C/T\sim$30J/molK$^2$-Ce, which, together with the corresponding cusp-like magnetization anomaly, indicates an antiferromagnetic (AFM) ground state with a N\'eel 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^*\approx$0.7T, much more effectively than expected from the Heisenberg model, indicating additional effects possibly due to frustration or residual Kondo screening.