High temperature bulk transport on floating-zone and Al-flux grown SmB₆ using Hall bar geometry

Samarium hexaboride is a correlated topological insulator in which strong interactions between f and d electrons lead to the opening of a small hybridization gap at the Fermi energy below about 100 K. At higher temperatures, at which the gap has not formed, the f-d interactions instead lead to strong skew scattering in the presence of a magnetic field. In addition, the bulk of SmB₆ is interesting in light of recent quantum oscillation results suggesting an unconventional bulk Fermi surface. We investigate the bulk of SmB₆ and the role of f-d interactions in its electronic properties via Hall coefficient and resistivity measurements from 4-400 K using a standard Hall bar geometry. Data are presented for a variety of samples, including pure SmB6 grown by both the aluminum flux method and the floating zone method, as well as SmB₆ intentionally grown with Sm deficiencies. We find a dramatic variation in the transport properties of these samples, most notably in the sign of the Hall coefficient above 60 K, even among pure samples grown by different methods, and we are continuing to investigate the origin of these variations.