# The influence of crystalline electric field on the magnetic properties of CeCd3X3 (X = P and As)

## TL;DR

This study investigates the magnetic properties of CeCd3X3 (X = P, As) compounds, revealing strong magnetic anisotropy driven by crystalline electric field effects, with experimental and theoretical analysis showing localized 4f-electron behavior despite some Kondo-like features.

## Contribution

The paper provides a detailed CEF model explaining magnetic anisotropy and compares it with previous studies, offering new insights into the magnetic behavior of CeCd3X3 compounds.

## Key findings

- Strong easy-plane magnetic anisotropy explained by CEF parameters.
- Less than 40% of Rln(2) entropy recovered at T_N.
- Electrical resistivity indicates metallic behavior with no Kondo contribution.

## Abstract

CeCd$_3$P$_3$ and CeCd$_3$As$_3$ compounds adopt the hexagonal ScAl$_3$C$_3$-type structure, where magnetic Ce ions on a triangular lattice order antiferromagnetically below $T_\text{N} \sim$0.42~K. Their crystalline electric field (CEF) level scheme has been determined by fitting magnetic susceptibility curves, magnetization isotherms, and Schottky anomalies in specific heat. The calculated results, incorporating the CEF excitation, Zeeman splitting, and molecular field, are in good agreement with the experimental data. The CEF model, with Ce$^{3+}$ ions in a trigonal symmetry, explains the strong easy-plane magnetic anisotropy that has been observed in this family of materials. A detailed examination of the CEF parameters suggests that the fourth order CEF parameter $B_{4}^{3}$ is responsible for the strong CEF induced magnetocrystalline anisotropy, with a large $ab$-plane moment and a small $c$-axis moment. The reliability of our CEF analysis is assessed by comparing the current study with earlier reports of CeCd$_{3}$As$_{3}$. For both CeCd$_{3}X_{3}$ ($X$ = P and As) compounds, less than 40 \% of $R\ln(2)$ magnetic entropy is recovered by $T_\text{N}$ and full $R\ln(2)$ entropy is achieved at the Weiss temperature $\theta_{p}$. Although the observed magnetic entropy is reminiscent of delocalized 4$f$-electron magnetism with significant Kondo screening, the electrical resistivity of these compounds follows a typical metallic behavior. Measurements of thermoelectric power further validate the absence of Kondo contribution in CeCd$_{3}X_{3}$.