¹²⁵ Te nuclear magnetic resonance and impedance spectroscopy study of topological insulator Bi <sub/>2</sub> Te <sub/>3</sub> nanoparticles mixed with insulating Al <sub/>2</sub> O <sub/>3</sub> nanoparticles

摘要： We have studied topological insulator Bi2Te3 nanoparticles mixed with insulating Al2O3 nanoparticles by means of 125Te nuclear magnetic resonance (NMR) and impedance spectroscopy. Our 125Te NMR lineshape measurements revealed the Knight shift of a satellite peak that increased with the mixing ratio of the Al2O3 nanoparticles, indicating that the mixing increases the surface-to-volume ratio of the Bi2Te3 nanoparticles. It is also shown that the impedance spectroscopy can be employed as a simple and effective means of distinguishing the surface electrical properties of the topological insulators in general.