Resistivity of Non-Galilean-Invariant Two-Dimensional Dirac Systems

We revisited the influence of electron-electron scattering on the resistivity of a two-dimensional system with a linear spectrum. In conventional systems with a parabolic spectrum, where umklapp scattering is either prohibited or ineffective due to the small Fermi surface, particle-particle scattering does not contribute to conductivity because it does not change the total momentum. However, within the framework of the Boltzmann kinetic model, we demonstrate that electron-electron scattering in Dirac systems can significantly contribute to conductivity, producing distinct temperature-dependent corrections: a T^{4} behavior at low temperatures and a T^{2} dependence at moderate temperatures. While the predicted T^{4} scaling is not observed experimentally-likely suppressed by dominant weak localization effects-the T^{2} scaling is clearly confirmed in our measurements. Specifically, temperature-dependent resistivity data from a gapless single-valley HgTe quantum well exhibit T^{2} corrections, which align well with theoretical predictions. Thus, we challenge the paradigm that the T^{2} term in resistivity is absent in single-band 2D metals.