Electronic properties of GeTe and Ag- or Sb-substituted GeTe studied by low-temperature Te-125 NMR

Article

关键词: GERMANIUM TELLURIDE;    THERMOELECTRIC-MATERIALS;    HIGH-PERFORMANCE;    ENHANCEMENT;    RELAXATION;    ALLOYS;    METALS;   

DOI  :  10.1103/PhysRevB.94.085203

来源: SCIE

【 摘 要 】

We have carried out Te-125 nuclear magnetic resonance (NMR) in a wide temperature range of 1.5-300 K to investigate the electronic properties of Ge50Te50, Ag2Ge48Te50, and Sb2Ge48Te50 from a microscopic point of view. From the temperature dependence of the NMR shift (K) and nuclear spin lattice relaxation rate (1/T-1), we found that two bands contribute to the physical properties of the materials. One band overlaps the Fermi level providing the metallic state where no strong electron correlations are revealed by Korringa analysis. The other band is separated from the Fermi level by an energy gap of E-g/k(B) similar to 67 K, which gives rise to semiconductorlike properties. First-principles calculation reveals that the metallic band originates from the Ge vacancy while the semiconductorlike band is related to the fine structure of the density of states near the Fermi level. Low-temperature Te-125 NMR data for the materials studied here clearly show that Ag substitution increases hole concentration while Sb substitution decreases it.

【 授权许可】

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