Rashba spin splitting and Dirac fermions in monolayer PtSe$_2$ nanoribbons

Bo-Wen Yu, Bang-Gui Liu

Published 2023-11-16Version 1

Two-dimensional (2D) semiconducting transition metal dichalcogenides have potential applications in various fields. Recently, it is shown experimentally and theoretically that monolayer PtSe$_2$ nanoflakes with neutral edges are stable. Here, we study PtSe$_2$ nanoribbons with the stable zigzag edges through first-principles investigation and find Rashba spin splitting and gapped relativstic electron dispersion in their valence and conduction bands near the Fermi level. Our analysis of atom-projected band structures and densities of states indicates that the part of bands originates mainly from the edges of the nanoribbons. It is also shown that there exists a SU(2) spin symmetry in both valence and conduction band edges, which implies persistent spin helix along the edges. Furthermore, we can achieve a Dirac electron model for an edge by combining the valence and conduction bands when the inter-edge interaction is week. These electronic systems could be useful for designing high-performance spintronic and optoelectronic applications.