Revealing the magnetic impurities induced electronic modification in the topological surface states

Topological insulators (TIs) host protected surface states (SS) with locked spin and momentum degrees of freedom. Breaking time-reversal symmetry could open a mass gap in the SS spectrum and is crucial for achieving numerous exotic electronic and spin effects. One promising approach to this goal is doping the TIs with magnetic dopants. However, a detailed understanding of the response of the topological SS to magnetic impurity perturbation has not been achieved yet. Here we study the magnetic impurities induced modification to the TI SS in the Vanadium- (V-) doped Sb2Te3 sample using scanning tunneling microscopy and spectroscopy. We observe unambiguous V impurity induced time-reversal symmetry breaking scattering around Dirac point. The hybridization between V impurity states and the SS is found to be weak. Furthermore, by employing the vanadium impurities at different depth as a unique scattering probing tool, the penetration depth and the nonuniformity of SS was revealed in sub-nanometer scale. Our results provide detailed insight into the

scattering mechanism of magnetic impurity with the TI SS and may pave the way to clarify the electronic structure of magnetic TIs, which will reconcile many current discrepancies in magnetic TI systems.