Ferromagnetic ordering of minority Ce$^{3+}$ spins in a quasi-skutterudite Ce${_3}$Os${_4}$Ge$_{13}$ single crystal

TL;DR

This study reveals site-disorder driven ferromagnetic ordering of minority Ce$^{3+}$ spins in Ce${_3}$Os${_4}$Ge$_{13}$ single crystals below 0.5 K, with non-Fermi liquid behavior observed at low temperatures.

Contribution

It demonstrates the ferromagnetic ordering of minority Ce$^{3+}$ spins due to site disorder in a quasi-skutterudite compound, highlighting the role of structural disorder in magnetic properties.

Findings

Ferromagnetic ordering occurs below 0.5 K.

Minority Ce$^{3+}$ spins are responsible for magnetism.

Non-Fermi liquid behavior observed at low temperatures.

Abstract

We report site disorder driven ferromagnetic ordering of nearly 8$\%$ Ce atoms in single crystalline Ce${_3}$Os${_4}$Ge$_{13}$ below 0.5~K. Ce${_3}$Os${_4}$Ge$_{13}$ crystallizes in a cubic structure with space group $\it{Pm\bar{3}n}$. The structural analysis shows the presence of site-disorder in the system, where 2(a) Ge site is partially occupied by the Ce atoms. Due to the small Ce $4f$-ligand hybridization, these Ce atoms are in the Ce$^{3+}$ (magnetic) state while rest of the Ce atoms in the unit cell are in Ce$^{4-\delta}$ (non-magnetic) state. The heat capacity shows a peak below 0.5~K corresponding to the ferromagnetic ordering of the Ce$^{3+}$ moments. The ferromagnetic ordering below 0.5~K is also seen in the ac-susceptibility data. At low temperatures (1.8~K$\leq T\leq 6$~K), the magnetization shows $log(T)$ dependence, whereas the resistivity shows power law ($T^n$) temperature dependence indicating the non-Fermi liquid behavior of the quasiparticles.