Transport in bilayer and multilayer graphene*

Using the semiclassical quantum Boltzmann equation (QBE), we
numerically calculate the DC transport properties of bilayer graphene
near charge neutrality [1]. We find, in contrast to prior discussions,
that phonon scattering is crucial even at temperatures below
40K. Nonetheless, electron-electron scattering still dominates over
phonon collisions allowing a hydrodynamic approach [2]. We introduce a
simple two-fluid hydrodynamic model of electrons and holes interacting
via Coulomb drag and compare our results to the full QBE
calculation. We show that the two-fluid model produces quantitatively
accurate results for conductivity, thermopower, and thermal
conductivity. Comparison is made to recent experiments [3], and
extensions of the theory are made for multilayer graphene [4].
References:

[1] Glenn Wagner, Dung X. Nguyen, Steven H. Simon, Phys. Rev. B 100,
245111 (2019)

[2] Glenn Wagner, Dung X. Nguyen, Steven H. Simon,
Phys. Rev. Lett. 124, 026601 (2020)

[3] Y. Nam, D.-K. Ki, D. Soler-Delgado, and A. F. Morpurgo, Nature
Physics 13, 1207 (2017)

[4] Dung X. Nguyen, Glenn Wagner, Steven H. Simon, Phys. Rev. B 101,
035117 (2020)