Angle dependence of Shubnikov-de Haas effect of CeOs$_4$Sb$_{12}$ and NdOs$_4$Sb$_{12}$*

The filled skutterudite compounds CeOs$_4$Sb$_{12}$, PrOs$_4$Sb$_{12}$, and NdOs$_4$Sb$_{12}$ are respectively a 1~K antiferromagnetic (AFM) Kondo insulator, a 1.85~K unconventional superconductor, and a 1~K mean-field type ferromagnet (FM), suggesting that superconductivity in PrOs$_4$Sb$_{12}$ may result from proximity to AFM and FM quantum-critical points. Fermi-surface measurements of NdOs$_4$Sb$_{12}$ and CeOs$_4$Sb$_{12}$ could therefore give insights into the pairing mechanism. A rotational skin-depth measurement probe developed at pulse field facilty of NHMFL is used to detect the angle depence of the Shubnikov-de Haas oscillations in single crystals of CeOs$_4$Sb$_{12}$ and NdOs$_4$Sb$_{12}$ at fields up to 60~T. The results indicate that NdOs$_4$Sb$_{12}$ has similar Fermi surfaces as those of PrOs$_4$Sb$_{12}$ and LaOs$_4$Sb$_{12}$ but the Fermi surface of CeOs$_4$Sb$_{12}$ is much different than those three compounds'. CeOs$_4$Sb$_{12}$ has similar Fermi surfaces as those of CeRu$_4$Sb$_{12}$.