Quantum interference and magnetotransport in moiré superlattices: quantum criticality and 1D localization

Moiré materials provide a highly tunable platform in which novel electronic phenomena can emerge. We study strained moiré materials in a uniform magnetic field and predict a sequence of transitions in the direction of electrical conductivity as magnetic field or strain is varied. This dramatic anisotropy reflects the emergence of nematic, one-dimensional physics at quantum Hall plateau transitions in strained moiré materials, along a direction which switches. We provide two complementary understandings of this phenomenon: in the strong field limit, the transitions map onto localization-delocalization transitions of Aubry-André-Harper chains; in weak field, the transitions are captured by Fabry-Pérot-like quantum interference in a semiclassical network model. These transitions should be observable in strained moir'e materials at realistic fields and low strain disorder, as well as unstrained systems with anisotropic Fermi surfaces.