Low-temperature antiferromagnetic order in orthorhombic CePdAl$_{3}$

TL;DR

This study reveals that single crystals of CePdAl3 with orthorhombic structure exhibit antiferromagnetic order below 5.6 K, contrasting with the tetragonal polycrystals, highlighting the impact of structural changes on magnetic and electronic properties.

Contribution

First demonstration of orthorhombic CePdAl3 single crystals showing antiferromagnetic order, contrasting with previously studied tetragonal polycrystals, emphasizing structure-property relationships.

Findings

Orthorhombic CePdAl3 orders antiferromagnetically below 5.6 K.

The specific heat shows a lambda anomaly at T_N.

Magnetic anisotropy and spin-flop transition observed.

Abstract

We report the magnetization, ac susceptibility, and specific heat of optically float-zoned single crystals of CePdAl$_{3}$. In comparison to the properties of polycrystalline CePdAl$_{3}$ reported in the literature, which displays a tetragonal crystal structure and no long-range magnetic order, our single crystals exhibit an orthorhombic structure ($Cmcm$) and order antiferromagnetically below a N\'eel temperature $T_{\rm N}$ = 5.6 K. The specific heat at zero-field shows a clear $\lambda$-type anomaly with a broad shoulder at $T_{\rm N}$. A conservative estimate of the Sommerfeld coefficient of the electronic specific heat, $\gamma = 121~\mathrm{mJ~K^{-2}~mol^{-1}}$, indicates a moderately enhanced heavy-fermion ground state. A twin microstructure evolves in the family of planes spanned by the basal plane lattice vectors $a_{\rm o}$ and $c_{\rm o}$, with the magnetic hard axis $b_{\rm o}$ common to all twins. The antiferromagnetic state is characterized by a strong magnetic anisotropy and a spin-flop transition induced under magnetic field along the easy direction, resulting in a complex magnetic phase diagram. Taken together our results reveal a high sensitivity of the magnetic and electronic properties of CePdAl$_{3}$ to its structural modifications.