Extremely high electron mobility in a phonon-glass semimetal

The silver chalcogenide semimetals are known for their appealing magnetoresistive properties. It is now shown that when copper silver selenide is doped with nickel, these properties are maintained, resulting in high electron mobilities and, in turn, a significant thermoelectric effect. The electron...

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Bibliographic Details
Published in:Nature materials 2013-06, Vol.12 (6), p.512-517
Main Authors: Ishiwata, S., Shiomi, Y., Lee, J. S., Bahramy, M. S., Suzuki, T., Uchida, M., Arita, R., Taguchi, Y., Tokura, Y.
Format: Article
Language:English
Subjects:
639/301/119
639/301/299/2736
Biomaterials
Chemical engineering
Condensed Matter Physics
Disorders
Electron mobility
Electrons
Lattices
letter
Magnetoresistance
Magnetoresistivity
Materials Science
Metalloids
Mobility
Nanotechnology
Optical and Electronic Materials
Quantum physics
Silver
Solar energy
Thermoelectricity
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Summary:The silver chalcogenide semimetals are known for their appealing magnetoresistive properties. It is now shown that when copper silver selenide is doped with nickel, these properties are maintained, resulting in high electron mobilities and, in turn, a significant thermoelectric effect. The electron mobility is one of the key parameters that characterize the charge-carrier transport properties of materials, as exemplified by the quantum Hall effect 1 as well as high-efficiency thermoelectric and solar energy conversions 2 , 3 . For thermoelectric applications, introduction of chemical disorder is an important strategy for reducing the phonon-mediated thermal conduction, but is usually accompanied by mobility degradation. Here, we show a multilayered semimetal β-CuAgSe overcoming such a trade-off between disorder and mobility. The polycrystalline ingot shows a giant positive magnetoresistance and Shubnikov de Haas oscillations, indicative of a high-mobility small electron pocket derived from the Ag s -electron band. Ni doping, which introduces chemical and lattice disorder, further enhances the electron mobility up to 90,000 cm 2  V −1  s −1 at 10 K, leading not only to a larger magnetoresistance but also a better thermoelectric figure of merit. This Ag-based layered semimetal with a glassy lattice is a new type of promising thermoelectric material suitable for chemical engineering.
ISSN:1476-1122
1476-4660
DOI:10.1038/nmat3621