  Earlier studies on the Kondo insulator SmB6 reveal the presence of a bulk
Kondo insulating gap between 30 - 50 K, and the emergence of a conducting
surface state only below 4 K. Here, we compare the two-coil mutual inductance
pick-up response of SmB6 single crystal with that of a conventional topological
insulator (TI), Bi2Se3 single crystal. From these studies we identify three
distinct temperature regimes for SmB6, viz., (i) T >= T*(~ 66 K), (ii) (40 K~)
T_g <= T < T*, and (iii) T < T_g. At T* in SmB6, we observe a peak in the
temperature-dependent AC pickup signal which corresponds to the peak in the
broad hump feature in the bulk DC susceptibility measurements and features in
the resistivity measurements. A dip in the pickup signal at T_g in SmB6
correlates with the evidence for the opening of a bulk Kondo gap in transport
measurements. Our study of the pickup signal in SmB6 suggests the presence of a
thin (submicron order thickness) high conducting surface layer from a
temperature just below T_g. In this T regime in SmB6, the pickup signal shows a
distinct square root frequency (f) dependence compared to the linear f
dependence found in Bi2Se3. Across all the different T regimes, distinct AC
frequency dependence and scaling properties are observed. Our results suggest
that above T*, weak exchange interactions cause electrons to scatter from
random ion sites. Electronic correlations gradually strengthen with the onset
of Kondo like hybridization, setting in from below T*, and at T_g, a strongly
correlated Kondo gap opens up in the bulk of the material. The appearance of
the thin high conducting surface layer is nearly coincident with the onset of
bulk Kondo insulating state below T_g in SmB6.
