Dimensional reduction from magnetic field in moiré superlattices

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 highly anisotropic electrical conductivity which switches easy-axis as magnetic field or strain is varied. The dramatic anisotropy reflects one-dimensional localization (dimensional reduction) of the electron wavefunctions along a crystal axis due to quantum interference effects. This can be understood in an effective one-dimensional quasiperiodic Aubry-André-like models, or in a complementary semiclassical picture. This phenomenon should be observable in strained moiré materials at realistic fields and low strain disorder, as well as unstrained systems with anisotropic Fermi surfaces.