Ellis Thompson: Microscopic origins of band topology and correlated states in twisted MoTe2

Date: Friday, May 2nd, 2025

Location: Elings Hall, room 1605

Time: 11:00 am - 12:00 pm

Microscopic origins of band topology and correlated states in twisted MoTe2

Abstract: Stacking two layers of molybdenum ditelluride (MoTe2) with a small interlayer twist creates a moiré superlattice that generates flat bands with nontrivial topology. When these bands are partially filled, strong Coulomb interactions lead to the emergence of integer and fractional quantum anomalous Hall (QAH) effects. Various experimental probes of these QAH states have solidified twisted MoTe2 (tMoTe2) as a fruitful platform to study the interplay between topology and electron-electron interactions, but device fabrication challenges have so far precluded studies on an atomic scale. The topology in tMoTe2 is predicted to arise from a sub-moiré scale texture of the layer pseudospin, which describes the layer polarization of the flat band wavefunctions. This makes atomic-scale probes such as scanning tunneling microscopy and spectroscopy (STM-S) crucial for understanding the nature of topology in this system. In this talk, I will present an STM-S investigation of the layer pseudospin texture in neutral tMoTe2. I will explain how we identify spectroscopic signatures of the flat bands and show that they exhibit a spatially varying layer polarization that closely matches theoretical predictions. These observations support the existence of a layer pseudospin texture in tMoTe2 and suggest a direct connection between its structural properties and band topology. Additionally, I will outline our progress towards studying the local properties of doped tMoTe2 by incorporating a graphene sensing layer into our STM device geometry. In future experiments, this may facilitate local imaging of QAH states along with competing topologically trivial states that arise from discrete translational symmetry breaking.