Gate-tuned quantum oscillations of topological surface states in β-Ag2Te

Sulaev, Azat; Zhu, Weiguang; Teo, K. L.; Wang, Lin-Lin

doi:10.1038/srep08062

Cited by 16 publications

(15 citation statements)

References 42 publications

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“…Figure 5 shows the Seebeck coefficient as a function of the temperature measured from Ag 2 Te nanowire. As previous studies reported that Ag 2 Te is -type semiconductor [1,6,15], the Seebeck coefficient reveals negative values, confirming that the majority of charge carriers are electrons. The Seebeck coefficients also drastically change at 130 ∘ C, similar trend of the resistance.…”

Section: Resultssupporting

confidence: 50%

Thermoelectric Properties of a Single Crystalline Ag₂Te Nanowire

Lee

Shin

Song

et al. 2017

Journal of Nanomaterials

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Silver chalcogenides have received much attention in potential thermoelectric materials research because of high carrier mobility and low effective mass. Among them, in Ag 2 Te, it was reported that the phase transition from monoclinic to cubic phase occurs at relatively low temperatures, so that extensive research for effective application using this material has been aroused. In this work, we investigated how 1-dimensional nanostructure affects the thermoelectric properties through as-synthesized single crystalline Ag 2 Te nanowires. Adopting well-defined thermoelectric MEMS device structure and transferring an individual Ag 2 Te nanowire, we measure electrical resistance and Seebeck coefficient as a function of temperature. When the phase changes from monoclinic to cubic, the resistance increases, while absolute Seebeck coefficient value decreases. These results are compared with previous reports for Ag 2 Te bulk and film, suggesting the increased density of states of the carriers due to nanowire structure.

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Section: Resultssupporting

confidence: 50%

Thermoelectric Properties of a Single Crystalline Ag₂Te Nanowire

Lee

Shin

Song

et al. 2017

Journal of Nanomaterials

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“…We mention here briefly that measurements of the resistance in two different geometries 24 indicated metallic topological surface states 5,8,9 below 100K. Since these are not expected to be a factor in the results presented here, we defer discussion of them to a later paper.…”

Section: B Electronic Transportmentioning

confidence: 80%

“…Topological surface states have been subsequently confirmed experimentally. 8,9 This work was followed by several high-pressure x-ray diffraction studies combined with firstprinciples electronic structure calculations, identifying four phases as the pressure is increased. [10][11][12] Phase I was determined to be semiconducting with topological conducting surface states, transforming into a semi-metallic Phase II through an isostructural transition identified as an electronic topological transition at 1.8-2.0 GPa.…”

Section: Introductionmentioning

confidence: 99%

Pressure-induced charge density wave phase in Ag2−δTe

et al. 2018

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Considerable excitement was generated by the observation of large and linear positive magnetoresistance (MR) in non-magnetic silver chalcogenides. Renewed interest in these materials was kindled by the discovery that Ag2Te in particular is a topological insulator with gapless linear Dirac-type surface states. High-pressure x-ray diffraction studies, combined with first-principles electronic structure calculations, have identified three phase transitions as the pressure is increased: an isostructural transition identified with an electronic topological transition followed by two structural phase transitions. These recent studies were carried out on nominally stoichiometric Ag2Te. For the present work we have prepared single-phase self-doped Ag2-dTe samples with a well-characterized silver deficit (d = 2.0´10-4) for structural and electrical transport measurements over extended ranges of pressure (0-43 GPa), temperature (2-300 K) and magnetic field (0-9 T). The temperature dependence of the resistivity exhibits anomalous behavior at 2.3 GPa, slightly above the isostructural transition, which we postulate is due to Fermi surface reconstruction associated with a charge-density-wave (CDW) phase. The anomaly is enhanced by the application of a 9T magnetic field and shifted to higher temperature, implying that the electronic Zeeman energy is sufficient to alter the gapping of the Fermi surface. A peak in the pressure dependence of the resistivity and a sudden drop in the pressure dependence of the mobility, occurring at 2.3 GPa, provide additional evidence for a CDW phase at pressures slightly above the isostructural transition.

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“…Moreover, it was recently shown to have characteristics associated with topologically nontrivial band inversion [8] and that if formed as a 2D crystal it may exhibit topological insulator characteristics [9]. Topological insulator behavior is also well established [10][11][12][13] in Ag 2 Se and Ag 2 Te. However the Cu 2−x Te phase diagram includes structures not fully determined in all cases, and there are several phase transitions at high temperatures [14,15] as the Te lattice adapts to superionic motion of the Cu ions [16].…”

Section: Introductionmentioning

confidence: 99%

NMR study of vacancy and structure-induced changes in Cu2-xTe

Sirusi

Page

Uher

et al. 2017

Journal of Physics and Chemistry of Solids

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We report Cu and Te NMR measurements on Cu 2−x Te with x between 0.13 and 0.22. Aided by powder x-ray analysis and computed NMR quadrupole shifts, a structure change near x = 0.20 was found consistent with structures reported by Baranova, with best fits to the β-I structure for x = 0.22 and β-III for smaller x. NMR T 1 and Hall effect results demonstrate p-type electronic behavior with filling of simple hole pockets induced by increased numbers of vacancies for both phases. Furthermore the Cu and Te chemical shifts are large and negative, as observed in topologically inverted semiconductors, with a splitting into two distinct local environments for both Cu and Te sites in the x = 0.22 structure. Cu T 1 results show a rapid decrease of the energy barrier for initiation of Cu ion hopping to 0.12 eV for x = 0.22, considerably smaller than observed at higher temperatures, indicating a tail of relatively mobile Cu ions which may be of significance for potential device applications.

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Gate-tuned quantum oscillations of topological surface states in β-Ag2Te

Cited by 16 publications

References 42 publications

Thermoelectric Properties of a Single Crystalline Ag₂Te Nanowire

Thermoelectric Properties of a Single Crystalline Ag₂Te Nanowire

Pressure-induced charge density wave phase in Ag2−δTe

NMR study of vacancy and structure-induced changes in Cu2-xTe

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Gate-tuned quantum oscillations of topological surface states in β-Ag2Te

Cited by 16 publications

References 42 publications

Thermoelectric Properties of a Single Crystalline Ag2Te Nanowire

Thermoelectric Properties of a Single Crystalline Ag2Te Nanowire

Pressure-induced charge density wave phase in Ag2−δTe

NMR study of vacancy and structure-induced changes in Cu2-xTe

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Product

Resources

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Thermoelectric Properties of a Single Crystalline Ag₂Te Nanowire

Thermoelectric Properties of a Single Crystalline Ag₂Te Nanowire