Angular Dependence of Quantum Oscillations in SmB$_6$

Recent proposals of low-dimensional electronic states in the Kondo insulator, SmB$_6$ have lead to renewed interest in the material. In this study we present quantum oscillation measurements of high quality single-crystals of SmB$_6$. Magnetic torque was measured in magnetic fields up to 40 T, allowing the observation of quantum oscillation frequencies ranging from 50 T to 15,000 T in multiple samples prepared by different groups. The size and the angular dependence of the oscillations indicate the striking concurrence of an electronically insulating bulk and a large, bulk Fermi surface. Comparison of the measured oscillations with similar measurements of metallic rare-earth hexaborides supports such a Fermi surface. Our model, previously employed for the metallic hexaborides, describes large ellipsoidally distorted spheres centred at X-points of the Brillouin zone, and smaller ellipsoids positioned at neck points, and gives a good account of the observed frequencies.