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arXiv · 1506.06338

Understanding Bulk Defects in Topological Insulators from Nuclear-Spin Interactions

Dimitrios Koumoulis·Belinda Leung·Thomas C. Chasapis·Robert Taylor·Daniel King Jr.·Mercouri G. Kanatzidis·Louis-S. Bouchard
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Abstract

Non-invasive local probes are needed to characterize bulk defects in binary and ternary chalcogenides. These defects contribute to the non-ideal behavior of topological insulators. We have studied bulk electronic properties via $^{125}$Te NMR in Bi$_2$Te$_3$, Sb$_2$Te$_3$, Bi$_{0.5}$Sb$_{1.5}$Te$_3$, Bi$_2$Te$_2$Se and Bi$_2$Te$_2$S. A distribution of defects gives rise to asymmetry in the powder lineshapes. We show how the Knight shift, line shape and spin-lattice relaxation report on carrier density, spin-orbit coupling and phase separation in the bulk. The present study confirms that the ordered ternary compound Bi$_2$Te$_2$Se is the best TI candidate material at the present time. Our results, which are in good agreement with transport and ARPES studies, help establish the NMR probe as a valuable method to characterize the bulk properties of these materials.

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Dimitrios Koumoulis, Belinda Leung, Thomas C. Chasapis, Robert Taylor, Daniel King Jr., Mercouri G. Kanatzidis, Louis-S. Bouchard. 2015-06-21. Understanding Bulk Defects in Topological Insulators from Nuclear-Spin Interactions. https://doi.org/10.1002/adfm.201302673

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