Theoretical Study of Hydrodynamic Magnetoresistance in Compensated Small Angle Twisted Heterostructures

Recent advancements in device fabrication techniques have enabled the production of exceptionally pristine sample devices, which has very low disorder. This results in the emergence of hydrodynamic transport behaviour in quantum materials, where charge carriers behaves like a fluid. Small angle twisted heterostructures offers a highly tunable platform to explore the crossover between a non-degenerate to a compensated electron-hole fluid, where electrons and holes experience strong mutual friction. In this theoretical work, we study the magnetoresistance in electron-hole friction dominated compensated twisted heterostructures, by combining a microscopic treatment of electron-electron interaction with a Navier-Stokes like equation. The signature of compensated semimetallic transport behaviour in twisted heterostructures has been observed in several experimental works, in particular zero-field transport study of small angle twisted bilayer graphene near charge neutrality point (CNP) [1] and a recent study of its close cousin, twisted double bilayer graphene, where large thermopower enhancement accompanied by large magnetoresistance at CNP in a weak magnetic fields much smaller than the extreme quantum limit are reported [2]. We shed light on the interplay between electron-hole friction, electron-phonon interaction, and disorder in magnetotransport and compare our theory with the recent experimental finding.

[1] Phys. Rev. Lett. 129, 206802 (2022).

[2] arXiv:2211.02654.