Size-dependent properties of Tl2 Se studied by NMR spectroscopy

A. M. Panich, M. Shao, C. L. Teske, W. Bensch

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14 Scopus citations

Abstract

We report on size-dependent properties of dithallium selenide, Tl2 Se. We have carried out a comparative nuclear magnetic resonance (NMR) study of Tl2 Se nanorods and bulk samples, measuring NMR spectra and spin-lattice relaxation rate of Tl203 and Tl205 isotopes. Though bulk Tl2 Se was reported to be a metal, the Korringa-like spin-lattice relaxation behavior is observed only at low temperatures and is transformed to an activation regime above ∼200 K. This finding is interpreted assuming a two-band model in the semimetallic compound. Our measurements show significant difference in the Knight shift and indirect nuclear exchange coupling for the bulk and nanorod Tl2 Se samples, reflecting noticeable distinction in their electronic structure. At that, Tl2 Se nanorods are semiconductors and exhibit a characteristic activation behavior in the spin-lattice relaxation rate due to the thermal excitation of carriers to the conduction band. The obtained size dependence of the Tl2 Se properties is interpreted in terms of the semimetal-semiconductor transformation due to the quantum confinement.

Original languageEnglish
Article number233305
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume74
Issue number23
DOIs
StatePublished - 18 Dec 2006

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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