Understanding bulk defects in topological insulators from nuclear-spin interactions

Dimitrios Koumoulis, Belinda Leung, Thomas C. Chasapis, Robert Taylor, Daniel King, Mercouri G. Kanatzidis, Louis S. Bouchard

Research output: Contribution to journalArticle

27 Citations (Scopus)

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. The bulk electronic properties are studied via 125Te NMR in Bi2Te3, Sb2Te 3, Bi0.5Sb1.5Te3, Bi 2Te2Se, and Bi2Te2S. A distribution of defects gives rise to asymmetry in the powder lineshapes. The Knight shift, line shape, and spin-lattice relaxation are investigated in terms of how they affect carrier density, spin-orbit coupling, and phase separation in the bulk. The present study confirms that the ordered ternary compound Bi 2Te2Se is the best topological insulator candidate material at the present time. These results, which are in good agreement with transport and angle-resolved photoemission spectroscopy studies, help establish the NMR probe as a valuable method to characterize the bulk properties of these materials. The role of bulk defects in topological insulators is investigated from the NMR standpoint. The NMR technique is validated against angle-resolved photoemission spectroscopy and transport measurements for the most commonly used binary and ternary topological insulators. Defect content is correlated with the NMR Knight shift and spin-lattice relaxation. NMR is a local probe which reports non-invasively on carrier concentration and dynamics.

Original languageEnglish
Pages (from-to)1519-1528
Number of pages10
JournalAdvanced Functional Materials
Volume24
Issue number11
DOIs
Publication statusPublished - Mar 19 2014

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Keywords

  • NMR
  • chalcogenides
  • defects
  • spin-lattice relaxation
  • topological insulators
  • vacancies

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

Cite this

Koumoulis, D., Leung, B., Chasapis, T. C., Taylor, R., King, D., Kanatzidis, M. G., & Bouchard, L. S. (2014). Understanding bulk defects in topological insulators from nuclear-spin interactions. Advanced Functional Materials, 24(11), 1519-1528. https://doi.org/10.1002/adfm.201302673