Stacking-order-dependent electronic properties of MoTe2/WSe2 moir\'e bilayers

TL;DR

This study calibrates optical SHG for MoTe2/WSe2 bilayers, clarifies how stacking order influences electronic properties, and reinterprets previous findings on topological and correlated phenomena.

Contribution

It establishes a reliable method to determine stacking order via SHG and links stacking configurations to electronic and magnetic behaviors in MoTe2/WSe2 bilayers.

Findings

Calibrated SHG for stacking order identification.

Linked stacking order to topological and correlated electronic phases.

Reinterpreted earlier results on Chern insulators and metal-insulator transitions.

Abstract

Transition metal dichalcogenide (TMD) moir\'e bilayers have realized a wide range of strongly correlated and topological phenomena. The physics in these materials is often sensitive to the interlayer stacking order. Polarization-resolved optical second harmonic generation (SHG) is the most used technique for stacking order characterization but unverified for most heterobilayers. Here we calibrate the optical SHG for angle-aligned MoTe2/WSe2 bilayers by the scanning transmission electron microscopy (STEM). We directly compare the transport and magnetic properties and the electronic phase diagram for two distinct stacking orders. With the calibrated stacking order assignment, we clarify the interpretation of earlier results, including the nature of the Chern insulator, mechanism of an electric-field-tuned metal-insulator transition at half band filling, and the Kondo lattice physics. Our work provides a consistent picture of the relation between the stacking order and the electronic properties of MoTe2/WSe2 moir\'e bilayers.