Related Experiment Video
Updated: Jun 7, 2026

Spectral and Angle-Resolved Magneto-Optical Characterization of Photonic Nanostructures
Published on: November 21, 2019
Twist-Angle-Dependent Excitons in Moiré MoTe2 Visualized by Cryogenic STEM and Monochromated EELS
Elizaveta Tiukalova1, Olugbenga Olunloyo2, Kai Xiao1
1Center for Nanophase Materials Sciences (CNMS), Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States.
None:
van der Waals twisted bilayers of transition-metal dichalcogenides exhibit diverse excitonic phenomena arising from moiré superlattices and lattice reconstruction. While interlayer strain and relaxation reshape their electronic bands, their nanoscale influence on the excitonic fine structure remains poorly understood. Here, we study the interplay between spin-orbit coupling (SOC) and the moiré lattice by probing excitons in H-type twisted (∼8-layer × 8-layer) MoTe2 using atomic-resolution scanning transmission electron microscopy (STEM) combined with monochromated electron energy loss spectroscopy (EELS) at cryogenic temperature. Spatially resolved spectra reveal moiré-site-dependent variations in excitonic absorption, including modulation of the XB exciton across the moiré unit cell. We find that SOC in MoTe2 increases with the twist angle within the studied range (2-4.5°), with the largest value observed at 4°. These findings establish the twist angle as a tunable parameter for SOC via moiré engineering and link local structural relaxation to excitonic fine structure in twisted MoTe2.
Related Concept Videos
Cryo-electron Microscopy
UV–Vis Spectroscopy: Molecular Electronic Transitions
Insensitive Nuclei Enhanced by Polarization Transfer (INEPT)
Total Internal Reflection Fluorescence Microscopy
Two-Dimensional Microscopy in Microbiology
Phase Contrast and Differential Interference Contrast Microscopy
In-phase-contrast microscopes, interference between light directly passing through a cell and light refracted by cellular components is used to create high-contrast, high-resolution images without staining. It is the oldest and simplest type of microscope that creates an image by altering the wavelengths of light rays passing through the specimen. Altered wavelength paths are created using an annular stop in the condenser. The annular stop produces a hollow cone of...

