Cluster glass behavior and magnetocaloric effect in the hexagonal polymorph of disordered Ce${}_2$PdGe${}_3$

Abstract

In this work, we study the hexagonal variant of the ${\text{Ce}}_2{\text{PdGe}}_3$ system that crystallizes in the ${\text{AlB}}_2$-type structure (space group $P6/mmm$, $hP3$) and exhibits cluster spin glass type behavior. The physical properties were studied by magnetization, heat capacity and electric resistivity, which showed that ${\text{AlB}}_2$-type ${\text{Ce}}_2{\text{PdGe}}_3$ ($h{\text{-Ce}}_2{\text{PdGe}}_3$) can be classified as a cluster glass material with the freezing temperature $T_f=3.44\text{ K}$ in contrast to the behavior of the previously described tetragonal variant, which shows a double antiferromagnetic transition at $T_{N1}=11\text{ K}$ and $T_{N2}=2.3\text{ K}$. The X-ray photoelectron spectroscopy measurements reveal that the $\text{Ce }4f$ states are well localized. In addition, we examine the magnetocaloric effect in this compound. The maximum values of magnetocaloric parameters appear in the vicinity of $7\text{–}9\text{ K}$. For a magnetic field change of $50\text{ kOe}$, the value of the change in magnetic entropy is $2.6(1){\text{ J kg}}^{-1}{\text{ K}}^{-1}$ and the adiabatic temperature change is $\sim 8\text{ K}$.