Ferromagnetism and possible heavy fermion behavior in single crystals of NdOs$_4$Sb$_{12}$

TL;DR

This study investigates NdOs$_4$Sb$_{12}$ single crystals, revealing ferromagnetic order near 0.9 K and signs of heavy fermion behavior with a large electronic specific heat coefficient.

Contribution

It provides the first detailed characterization of ferromagnetism and heavy fermion indications in NdOs$_4$Sb$_{12}$, expanding understanding of filled-skutterudite compounds.

Findings

Ferromagnetic transition at ~0.9 K observed in resistivity, magnetization, and heat capacity.

Large electronic specific heat coefficient γ ≈ 520 mJ/mol-K^2 indicating heavy fermion behavior.

Mean-field ferromagnetism confirmed by Arrott-plot analysis.

Abstract

Single crystals of the filled-skutterudite compound NdOs$_4$Sb$_{12}$ have been investigated by means of electrical resistivity, magnetization, and specific heat measurements. The NdOs$_4$Sb$_{12}$ crystals have the LaFe$_4$P$_{12}$-type cubic structure with a lattice parameter of 9.3 \AA. Possible heavy-fermion behavior is inferred from specific heat measurements, which reveal a large electronic specific heat coefficient $\gamma \approx 520$ mJ/mol-K$^2$, corresponding to an effective mass $m^* \sim$ 98 $m_e$. Features related to a ferromagnetic transition at {$\sim$ 0.9 K} can be observed in electrical resistivity, magnetization and specific heat. Conventional Arrott-plot analysis indicates that NdOs$_4$Sb$_{12}$ conforms to mean-field ferromagnetism.