Related Experiment Video
Updated: Aug 2, 2026

Using Microwave and Macroscopic Samples of Dielectric Solids to Study the Photonic Properties of Disordered Photonic Bandgap Materials
Published on: September 26, 2014
Topological Exciton Bands in Moiré Heterojunctions
Fengcheng Wu1,2, Timothy Lovorn1, A H MacDonald1
1Department of Physics, University of Texas at Austin, Austin, Texas 78712, USA.
Abstract:
Moiré patterns are common in van der Waals heterostructures and can be used to apply periodic potentials to elementary excitations. We show that the optical absorption spectrum of transition metal dichalcogenide bilayers is profoundly altered by long period moiré patterns that introduce twist-angle dependent satellite excitonic peaks. Topological exciton bands with nonzero Chern numbers that support chiral excitonic edge states can be engineered by combining three ingredients: (i) the valley Berry phase induced by electron-hole exchange interactions, (ii) the moiré potential, and (iii) the valley Zeeman field.
More Related Videos
Related Concept Videos
UV–Vis Spectroscopy: Molecular Electronic Transitions
IR Absorption Frequency: Hybridization
Among the sp, sp2, and sp3 hybridized orbitals, sp orbitals have the maximum s character (50%). Consequently, the electrons are held more closely to the nucleus, resulting in stronger and shorter C–H bonds that stretch at a...
IR Absorption Frequency: Delocalization
In IR spectroscopy,...
Energy Bands in Solids
Band Formation:
When atoms are brought close together, as in a solid, these discrete energy levels begin to split due to the overlap of electron orbitals from adjacent atoms. This split occurs because of the Pauli exclusion principle, which states that no two...
P-N junction
Metal-Semiconductor Junctions
Schottky Barriers
Schottky barriers arise when a metal with a work function (Φm) contacts a semiconductor with a different work function (Φs). Initially, electrons transfer until the Fermi levels of the metal and semiconductor align at equilibrium. For instance, if Φm > Φs, the semiconductor Fermi level is higher than the metal's before contact. The semiconductor's...

