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Extremely high electron mobility in a phonon-glass semimetal

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The electron mobility is one of the key parameters that characterize the charge-carrier transport properties of materials, as exemplified by the quantum Hall effect1 as well as high-efficiency thermoelectric and solar energy conversions2,3. 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 cm2 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.

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Figure 1: Structure and transport properties.
Figure 2: GMR and Hall resistance.
Figure 3: Two-carrier model analyses for the conductivity tensors.
Figure 4: Experimental and theoretical characterization of conduction electrons.

Change history

  • 29 April 2013

    In the version of this Letter originally published online, the present address of the author J. S. Lee was not included; it should have read 'Department of Physics and Photon Science, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, Korea'. This error has been corrected in all versions of the Letter.


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The authors thank D. Okuyama and T. Arima for experimental support and thank J. G. Checkelsky, A. Tsukazaki, F. Kagawa and N. Kanazawa for useful comments. This study was in part supported by a Grant-in-Aid for Scientific Research (Grant No. 23685014) from the MEXT, and by the Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST Program), Japan.

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Authors and Affiliations



S.I. and Y. Tokura conceived the study and wrote the paper. S.I. prepared the samples and performed the transport measurements. Y.S. and M.U. designed the thermoelectric measurement systems. T.S. and Y. Taguchi performed thermoelectric measurements at high temperatures. J.S.L. worked on the optical study. M.S.B. and R.A. performed band calculations.

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Correspondence to S. Ishiwata.

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Ishiwata, S., Shiomi, Y., Lee, J. et al. Extremely high electron mobility in a phonon-glass semimetal. Nature Mater 12, 512–517 (2013).

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