The role of dimensionality in the Kondo Ce$TX_{2}$ family: the case of CeCd$_{1-\delta}$Sb$_{2}$

TL;DR

This study investigates the magnetic properties of CeCd$_{1- ext{delta}}$Sb$_{2}$, revealing ferromagnetic order and a distinct crystal electric field scheme, highlighting the influence of structural dimensionality in the Ce$TX_2$ family.

Contribution

It provides the first detailed analysis of CeCd$_{1- ext{delta}}$Sb$_{2}$'s magnetic behavior, demonstrating ferromagnetism and a unique CEF scheme, contrasting with other antiferromagnetic members.

Findings

CeCd$_{1- ext{delta}}$Sb$_{2}$ exhibits ferromagnetic order at 3 K.

A distinct CEF scheme with a pure | extpm 1/2 angle ground state was identified.

Structural dimensionality influences magnetic ground states in the Ce$TX_2$ family.

Abstract

Motivated by the presence of competing magnetic interactions in the heavy fermion family Ce$TX_2$ ($T$ = transition metal, $X$ = pnictogen), here we study the novel parent compound CeCd$_{1-\delta}$Sb$_{2}$ by combining magnetization, electrical resistivity, and heat-capacity measurements. Contrary to the antiferromagnetic (AFM) ground state observed in most members of this family, the magnetic properties of our CeCd$_{1-\delta}$Sb$_{2}$ single crystals revealed a ferromagnetic (FM) ordering at $T_{\rm c}$ = 3 K with an unusual soft behavior. By using a mean field model including anisotropic nearest-neighbors interactions and the tetragonal crystalline electric field (CEF) Hamiltonian, a systematic analysis of our macroscopic data was obtained. Our fits allowed us to extract a simple but very distinct CEF scheme, as compared to the AFM counterparts. As in the previously studied ferromagnet CeAgSb$_{2}$, a pure $|\pm 1/2 \rangle$ ground state is realized, hinting at a general trend within the ferromagnetic members. We propose a general scenario for the understanding of the magnetism in this family of compounds based on the subtle changes of dimensionality in the crystal structure.