Staggered pseudo magnetic field in twisted transition metal dichalcogenides: Physical origin and experimental consequences

Strong magnetic fields profoundly affect the quantum physics of charged particles, as seen for example by the integer and fractionally quantized Hall effects, and the fractal "Hofstadter butterfly"spectrum of electrons in the presence of a periodic potential and a magnetic field. Intrinsic physics can lead to effects equivalent to those produced by an externally applied magnetic field. Examples include the "staggered flux"phases emerging in some theories of quantum spin liquids and the Chern insulator behavior of twisted bilayer graphene when valley symmetry is broken. In this Letter we show that when two layers of the transition metal dichalcogenide material WSe2 are stacked at a small relative twist angle to form a moiré bilayer, the resulting low-energy physics can be understood in terms of electrons moving in a strong and tunable staggered flux. We predict experimental consequences including sign reversals of the Hall coefficient on application of an interlayer potential and spin currents appearing at the sample edges and interfaces.