Electrical and thermoelectrical properties of undoped Bi2Te3-Sb2Te3 and Bi2Te3-Sb2Te3-Sb2Se3 single crystals

Jeon, H.W.; Ha, Heon Phil; Hyun, Dow-Bin; Shim, Jae-Dong

doi:10.1016/0022-3697(91)90151-o

Cited by 146 publications

(71 citation statements)

References 14 publications

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“…2 (Fig. 2, Inset) are reasonably close to values previously reported (27,28) order as observed here. Higher carrier concentrations at higher temperatures (150-288 K) have been commonly observed in narrow-gap semiconductors and are attributed to a cross-over from a thermally activated regime to a saturation regime.…”

Section: Resultssupporting

confidence: 90%

Nanoscale β-nuclear magnetic resonance depth imaging of topological insulators

Koumoulis

Morris

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Considerable evidence suggests that variations in the properties of topological insulators (TIs) at the nanoscale and at interfaces can strongly affect the physics of topological materials. Therefore, a detailed understanding of surface states and interface coupling is crucial to the search for and applications of new topological phases of matter. Currently, no methods can provide depth profiling near surfaces or at interfaces of topologically inequivalent materials. Such a method could advance the study of interactions. Herein, we present a noninvasive depth-profiling technique based on β-detected NMR (β-NMR) spectroscopy of radioactive 8 Li + ions that can provide "one-dimensional imaging" in films of fixed thickness and generates nanoscale views of the electronic wavefunctions and magnetic order at topological surfaces and interfaces. By mapping the 8 Li nuclear resonance near the surface and 10-nm deep into the bulk of pure and Cr-doped bismuth antimony telluride films, we provide signatures related to the TI properties and their topological nontrivial characteristics that affect the electronnuclear hyperfine field, the metallic shift, and magnetic order. These nanoscale variations in β-NMR parameters reflect the unconventional properties of the topological materials under study, and understanding the role of heterogeneities is expected to lead to the discovery of novel phenomena involving quantum materials.topological insulator | nuclear magnetic resonance | depth profiling | condensed matter physics | nanoscale physics T opological insulators (TIs) are narrow-gap semiconductor materials that are insulating in the bulk and conductive on their surface. The constituent atoms are typically heavy elements with large spin-orbit coupling (SOC). In time-reversal-invariant materials, the electronic structure of TIs is characterized by band inversions from strong SOC at an odd number of time-reversalinvariant momenta in the bulk Brillouin zone. Unlike metals or ordinary insulators (OIs), charge carriers in TIs evolve from metallic to insulating as a function of depth from the surface. The surface-state electrons are characterized by a suppression of backscattering and an intrinsic chirality of spin-momentum locking, making them of interest in spintronics. A number of theoretical predictions of experimental observations have been made including Majorana fermions, condensed-matter axions, and quantized Hall conductance (1, 2). Heterostructure engineering, where a crystal is formed consisting of a sequence of different building blocks (for example, alternating TI and OI layers), can trigger new physical phenomena such as TIs with enhanced bulk band gaps (3) or Weyl semimetals (4).Because topological materials are characterized by sharp changes in electronic properties at their surfaces and at interfaces with other materials, sensitive techniques are required to probe electronic and magnetic properties in a spatially resolved manner down to the atomic length scale. It has become clear that TI properties are spatially de...

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Section: Resultssupporting

confidence: 90%

Nanoscale β-nuclear magnetic resonance depth imaging of topological insulators

Koumoulis

Morris

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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“…2 and 3) at room temperature (T max ¼ 300 K), yielding a maximum Seebeck coefficient near 230 lV/K-a reasonable estimate. [4][5][6][7] While the Goldsmid-Sharp gap serves as a quick estimate of the band gap in a given material, it is important to understand where deviations might occur when using this analysis. In Goldsmid-Sharp's full equation, the weighted mobility ra-…”

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confidence: 99%

Band gap estimation from temperature dependent Seebeck measurement—Deviations from the 2e|S|maxTmax relation

Gibbs

Kim

Wang

et al. 2015

Applied Physics Letters

200

120

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“…In summary, we have checked the electronic structure and TE properties of GBT compounds for [59][60][61][62][63][64], the p-type GBT with m = 8, n = 1 is predicted to have best ZT upto 1.4 near room temperature. The results show that band engineering by strain and quantumconfinement effect could enhance the TE performances.…”

Section: Discussionmentioning

confidence: 99%

OptimizedZTofBi2Te3−GeTecompoun

2016

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We predict the thermoelectric properties of layered [GeTe] m [Bi 2 Te 3 ] n (GBT) compounds (1 ≤ m ≤ 8, 1 ≤ n ≤ 3), using first-principles-Boltzmann transport calculations of the homogeneous (Bi 2 Te 3 and GeTe) data. The lattice strain and the quantum-confinement effects of compounds evolve the bandgap structures, resulting in asymmetric and large Seebeck coefficient, at high GeTe content.Using semi-empirical calculations of electron scattering rate 1/ ! , dominated by electron-acoustic phonon scattering, we reproduce reported TE properties of GBT compounds. We predict that due to small Seebeck coefficient, the GBT compounds with high n-and p-type doping (~10 20 cm -3 ), do not have high ZT near room temperature. However, we predict that the moderately-doped (~10 19 cm -3 ), p-type GBT compounds have enhanced ZT ≈ 1.4 near room temperature. *

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Electrical and thermoelectrical properties of undoped Bi2Te3-Sb2Te3 and Bi2Te3-Sb2Te3-Sb2Se3 single crystals

Cited by 146 publications

References 14 publications

Nanoscale β-nuclear magnetic resonance depth imaging of topological insulators

Nanoscale β-nuclear magnetic resonance depth imaging of topological insulators

Band gap estimation from temperature dependent Seebeck measurement—Deviations from the 2e|S|maxTmax relation

OptimizedZTofBi2Te3−GeTecompoun

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