Extremely high electron mobility in a phonon-glass semimetal

• Published in: Nature materials Vol. 12; no. 6; pp. 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: Journal Article
• Language: English
• Published: England Nature Publishing Group 01.06.2013
• Subjects: Chemical engineering; Disorders; Electron mobility; Electrons; Lattices; Magnetoresistance; Magnetoresistivity; Materials science; Metalloids; Quantum physics; Silver; Thermoelectricity
• ISSN: 1476-1122; 1476-4660
• DOI: 10.1038/nmat3621

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 as well as high-efficiency thermoelectric and solar energy conversions. 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.