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arXiv · 1301.2819

NMR Probe of Metallic States in Nanoscale Topological Insulators

Dimitrios Koumoulis·Thomas C. Chasapis·Robert E. Taylor·Michael P. Lake·Danny King·Nanette N. Jarenwattananon·Gregory A. Fiete·Mercouri G. Kanatzidis·Louis-S. Bouchard
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Abstract

A 125Te NMR study of bismuth telluride nanoparticles as function of particle size revealed that the spin-lattice relaxation is enhanced below 33 nm, accompanied by a transition of NMR spectra from single to 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 140-420K, micrometer particles do so only below 200K. The results reveal increased metallicity of these nanoscale topological insulators in the limit of higher surface-to-volume ratios.

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Dimitrios Koumoulis, Thomas C. Chasapis, Robert E. Taylor, Michael P. Lake, Danny King, Nanette N. Jarenwattananon, Gregory A. Fiete, Mercouri G. Kanatzidis, Louis-S. Bouchard. 2013-01-13. NMR Probe of Metallic States in Nanoscale Topological Insulators. https://doi.org/10.1103/physrevlett.110.026602

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