Site-specific symmetry sensitivity of angle-resolved photoemission spectroscopy in layered palladium diselenide

Abstract

Two-dimensional (2D) materials with puckered layer morphology are promising candidates for next-generation optoelectronics devices owing to their anisotropic response to external perturbations and wide band gap tunability with the number of layers. Among them, palladium diselenide (PdSe2) is an emerging 2D transition-metal dichalcogenide, with a band gap ranging from ∼ 1.3 eV in the monolayer to a predicted semimetallic behaviour in the bulk. Here, we use angle-resolved photoemission spectroscopy to explore the electronic band structure of PdSe2 with energy and momentum resolution. Our measurements reveal the semiconducting nature of the bulk. Furthermore, constant binding-energy maps of reciprocal space display a remarkable site-specific sensitivity to the atomic arrangement and its symmetry. Supported by density functional theory calculations, we ascribe this effect to the inherent orbital character of the electronic band structure. These results not only provide a deeper understanding of the electronic configuration of PdSe2, but also establish additional capabilities of photoemission spectroscopy.