2025/10/02 by Seungil Baek, Baek, Seungil, Jun Yeong Jung +3
Engineering · Materials Science · #2D Materials and Applications #Absorption edge #Chalcogenide Semiconductor Thin Films #Conduction band #FOS: Physical sciences #Hexagonal crystal system #Materials Science (cond-mat.mtrl-sci) #Monolayer #Organic and Molecular Conductors Research #Parity (physics) #Transition metal #Valence (chemistry) #Valence band
paper · pdf · doi:10.48550/arxiv.2510.01575
published in arXiv (Cornell University) (Cornell University)
openalex publication_date 2025/10/02 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The optical selection rule states that opposite parity between the valence and conduction bands is required for optical absorption to occur. However, monolayer hexagonal transition metal dichalcogenides (h-TMDs) such as MoS2 exhibit pronounced optical absorption despite their nominally dipole-forbidden d-d transitions. In this Letter, we elucidate a parity inversion mechanism through which obstruction-driven band inversion promotes dipole-allowed optical transitions near the band edge in monolayer h-TMDs. By comparing trivial and obstructed atomic limit phases, we show that intersite interactions between hybridized d orbitals induce parity inversion. Our results provide a novel approach to tuning optical properties through parity control, bridging the gap between topology and light-matter interaction.