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

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 Å. 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 $m^{\ast }\sim$ 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.

9 pages, 9 figures. Currently submitted to Physical Review B