Spin Fluctuations at the Surface of Strongly Correlated Topological Insulator SmB 6

The low temperature (T < 5 K) electron spin resonance in topological Kondo insulator SmB6 is investigated. It is shown that spin relaxation time of the paramagnetic centers responsible for low temperature electron spin resonance in SmB6 is about ~ 10−8 s, which exceeds by five orders of magnitude the widely accepted spin and charge fluctuation time ~ 10−13 s in the homogeneous mixed valence state of this material. This discrepancy may be attributed to the formation of the specific paramagnetic centers in the sample surface–spin polarons.