LOW-TEMPERATURE RESISTIVITY OF VALENCE FLUCTUATION COMPOUND SMB6

The electrical resistivity of SmB6 single crystal has been measured do wn to 50 mK. At temperatures below 3 K a rather complicated behavior o f electrical conductivity including the temperature activated and temp erature non-activated term was observed. The activated conductivity te rm can be well described by sigma = c exp [-(T0/T)x] with x equal to o r close to 1 and T0 = 2.68 K, while the non-activated conductivity is dominating below about 0.2 K and shows presence of the logarithmic Kon do-like contribution to resistivity. To explain observed results a mod el based on introducing a fine structure into the hybridization gap is proposed. This fine structure may consist of two narrow low-density b ands with a gap between them of few tenths of meV wide.