Nuclear magnetic resonance study of a Bi2Te3 topological insulator

Abstract

he results of the nuclear magnetic resonance (NMR) study of a grown high-quality Bi2Te3 semiconductor single crystal have been presented. Signals from the Te-125 isotope were detected by the spin echo method in the range from 10 K to room temperature. It was found that the NMR spectrum consists of two lines. The line with a positive shift of the resonance frequency corresponded to the bulk of the sample. The line with a negative shift was interpreted as a signal from the surface of the single crystal. The temperature and orientational dependences of the positions of the NMR line of nuclei in the bulk of the crystal were studied. It was shown that the shifts are mainly determined by the Knight shift due to the interaction with mobile charge carriers. The thermoactivation character of the concentration of mobile charges in the crystal under study, which corresponds to the intrinsic conductance, was proved, and the energy parameters of the thermoactivation processes were calculated.