Magnetohydrodynamics and electron-electron interaction of massless Dirac fermions

Abstract

The magnetotransport properties of massless Dirac fermions in a gapless HgTe quantum well are investigated. In samples with narrow channels, a large negative magnetoresistance with a Lorentzian profile is observed, which is interpreted as a manifestation of electron viscosity due to an electron-electron interaction. A comparison of experiment with theory yields the shear stress relaxation time of the Dirac fermions caused by electron-electron scattering.