LARGE LOW-TEMPERATURE HALL-EFFECT AND RESISTIVITY IN MIXED-VALENT SMB6

The Hall coefficient RH has been measured between 2 and 300 K for small crystals of SmB6 in which the resistivity ρ at 4 K is nearly 104 times greater than its 300-K value of 290 μΩ cm. Significant differences from previous results reported for samples with a much smaller low-temperature resistivity rise have been found. It is shown that the size of the resistivity increase precludes its being ascribed to a scattering mechanism for a metallic number of carriers, and that the size of RH implies numbers of holes and electrons less than ∼5 × 1017/cm3 at 4 K. The origin of the low-temperature residual conductivity is discussed. © 1979 The American Physical Society.