Giant nonlinear Hall effect in twisted bilayer WSe2

They report a giant nonlinear Hall generation efficiency of 1000 V-1 in small-angle-twisted bilayer WSe2, which is two orders of magnitude higher than previous records, and interpret the result by the correlation induced continuous Mott transition effect. The recently discovered nonlinear Hall effect (NHE) in a few non-interacting systems provides a novel mechanism for generating second-harmonic electrical Hall signals under time-reversal-symmetric conditions. Here, we introduce a new approach to engineering an NHE by using twisted moire structures. We found that the twisted WSe2 bilayer exhibited an NHE when the Fermi level was tuned to the moire flat bands. When the first moire band was half-filled, the nonlinear Hall signal exhibited a sharp peak with a generation efficiency that was at least two orders of magnitude greater than those obtained in previous experiments. We discuss the possible origins of the diverging generation efficiency in twisted WSe2 based on resistivity measurements, such as moire-interface-induced correlation effects and mass-diverging-type continuous Mott transition. This study demonstrates not only how interaction effects can combine with Berry curvature dipoles to produce novel quantum phenomena, but also the potential of NHE measurements as a new tool for studying quantum criticality.

Automated summary

This study reports a significant breakthrough in the efficiency of nonlinear Hall generation in small-angle-twisted bilayer WSe2, reaching 1000 V-1, which is a hundred times higher than the previous records. The researchers explained this result through the correlation-induced continuous Mott transition effect.