Bulk Nuclear Magnetic Resonance of Topological Insulators

Topological insulators are materials that are insulating in the bulk but remain conducting on the surface. We present $^{209} $Bi nuclear magnetic resonance (NMR) spectra and relaxation rate data on single crystals of Bi$_{2}$Se$_{3}$ and Bi$_{2} $Te$_{2}$Se. Our preliminary data reveal significant differences in the local electric field gradient between these two materials, and indicate a large anisotropy in the spin- lattice and spin-spin relaxation rates.