Revealing orbital texture of grey arsenic through linear dichroism in multidimensional photoemission spectroscopy

Two-dimensional (2D) layered material grey arsenic exhibits great potential for electronic and optoelectronics devices. Identifying the orbital texture in the electronic energy bands close to Fermi level is crucial for understanding and further manipulating the optoelectronic properties of grey arsenic. In this work, we investigate the orbital properties from bulk-state and surface-state of grey arsenic by using multidimensional angle-resolved photoemission spectroscopy, under different light polarization and crystal orientation conditions. Furthermore, by combining the experimental results with first-principles calculations based on density functional theory (DFT), we reveal that both the surface and bulk states of grey arsenic contain 4 s, 4p_x, 4p_y and 4p_z orbitals, but the orbital ratios are different. Our study offers new insight into the orbital nature of grey arsenic and also paves the way for investigation of orbital properties in other 2D materials.