Intragap states inSmB6

Abstract
The results of wide-range measurements of the low-frequency, rf, and microwave conductivity in the typical mixed-valent narrow-gap semiconductor samarium hexaboride are presented. The established steplike anomaly of conductivity σ(ν) around 10 GHz is discussed in the framework of the exciton-polaron approach and coherent-state formation in SmB6 at helium temperatures. A combined analysis of the dc- and wide-range ac-transport characteristics and dielectric permittivity data at low temperatures is developed.