Dresden 2026 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 24: 2D Materials IV – Emerging materials and properties

HL 24.12: Vortrag

Mittwoch, 11. März 2026, 12:30–12:45, POT/0081

Circular Dichroism ARPES Reveals Orbital Chirality in Single-Layer TMDs — •Shubham Patel, Luke Pimlott, and Habib Rostami — Department of Physics, University of Bath, Claverton Down BA2 7AY, United Kingdom

The electron wavefunctions in momentum space are fundamental to understanding the microscopic physical properties of solids. Circular dichroism (CD), a key feature observable in angle-resolved photoemission spectroscopy (ARPES) [1]. Recent experimental investigations have indicated a direct relationship between CD-ARPES and the Berry curvature of electronic bands [2], motivating theoretical efforts to interpret CD within this framework. The Berry curvature-based approach fails to capture certain critical sign-reversal features near the time-reversal-invariant K(K') points. Moreover, this method lacks dependence on the photon energy of the incident light, as it is derived purely from the momentum-space wavefunction characteristics. In the present work, we adopt this plane wave approximation to compute CD-ARPES spectra and find excellent agreement with experimental observations. We solve tight-binding Hamiltonian for single-layer TMDs, and generalize the dipole matrix elements. This formalism successfully captures the sign-changing behavior of CD near the K(K') points, a feature absent in the Berry curvature approach, and provide a control on tunability of the dichroic response with the photon energy. Notably, our theoretical approach offers an alternative explanation that differs from the Berry curvature-based framework.

[1] PRL 110, 216801 (2013) [2] PRL 121, 186401 (2018)

Keywords: Circular Dichroism ARPES; Dipole moment; Transition metal dichalcogenides; DFT