NMR probe of metallic states in nanoscale topological insulators

A 125Te NMR study of bismuth telluride nanoparticles as a function of particle size revealed that the spin-lattice relaxation is enhanced below 33 nm, accompanied by a transition of NMR spectra from the single to the bimodal regime. The satellite peak features a negative Knight shift and higher rela...

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Bibliographic Details
Published in:Physical review letters 2013-01, Vol.110 (2), p.026602-026602, Article 026602
Main Authors: Koumoulis, Dimitrios, Chasapis, Thomas C, Taylor, Robert E, Lake, Michael P, King, Danny, Jarenwattananon, Nanette N, Fiete, Gregory A, Kanatzidis, Mercouri G, Bouchard, Louis-S
Format: Article
Language:English
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Summary:A 125Te NMR study of bismuth telluride nanoparticles as a function of particle size revealed that the spin-lattice relaxation is enhanced below 33 nm, accompanied by a transition of NMR spectra from the single to the bimodal regime. The satellite peak features a negative Knight shift and higher relaxivity, consistent with core polarization from p-band carriers. Whereas nanocrystals follow a Korringa law in the range 140-420 K, micrometer particles do so only below 200 K. The results reveal increased metallicity of these nanoscale topological insulators in the limit of higher surface-to-volume ratios.
ISSN:0031-9007
1079-7114
DOI:10.1103/physrevlett.110.026602