Effective Mass in Bilayer Graphene at Low Carrier Densities: the Role of Potential Disorder and Electron-Electron Interaction
| Autor: | Takashi Taniguchi, Steven G. Louie, Jun Zhu, Jiefang Li, Ke Zou, D. J. Seiwell, Kenji Watanabe, Liang Z. Tan, Adam Stabile |
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| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
Physics
Condensed matter physics Condensed Matter - Mesoscale and Nanoscale Physics FOS: Physical sciences Electron interaction Hexagonal boron nitride 02 engineering and technology Electron 021001 nanoscience & nanotechnology 01 natural sciences Charge-carrier density Effective mass (solid-state physics) Mesoscale and Nanoscale Physics (cond-mat.mes-hall) 0103 physical sciences 010306 general physics 0210 nano-technology Fermi gas Bilayer graphene |
| Popis: | In a two-dimensional electron gas, the electron-electron interaction generally becomes stronger at lower carrier densities and renormalizes the Fermi-liquid parameters, such as the effective mass of carriers. We combine experiment and theory to study the effective masses of electrons and holes ${m}_{e}^{*}$ and ${m}_{h}^{*}$ in bilayer graphene in the low carrier density regime on the order of $1\phantom{\rule{0.16em}{0ex}}\ifmmode\times\else\texttimes\fi{}\phantom{\rule{0.16em}{0ex}}{10}^{11}\phantom{\rule{0.28em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}2}$. Measurements use temperature-dependent low-field Shubnikov\char21{}de Haas oscillations observed in high-mobility hexagonal boron nitride supported samples. We find that while ${m}_{e}^{*}$ follows a tight-binding description in the whole density range, ${m}_{h}^{*}$ starts to drop rapidly below the tight-binding description at a carrier density of $n=\phantom{\rule{0.16em}{0ex}}6\phantom{\rule{0.16em}{0ex}}\ifmmode\times\else\texttimes\fi{}\phantom{\rule{0.16em}{0ex}}{10}^{11}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}2}$ and exhibits a strong suppression of 30% when $n$ reaches $2\phantom{\rule{0.16em}{0ex}}\ifmmode\times\else\texttimes\fi{}\phantom{\rule{0.16em}{0ex}}{10}^{11}\phantom{\rule{0.28em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}2}$. Contributions from the electron-electron interaction alone, evaluated using several different approximations, cannot explain the experimental trend. Instead, the effect of the potential fluctuation and the resulting electron-hole puddles play a crucial role. Calculations including both the electron-electron interaction and disorder effects explain the experimental data qualitatively and quantitatively. This Rapid Communication reveals an unusual disorder effect unique to two-dimensional semimetallic systems. |
| Databáze: | OpenAIRE |
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