Spin polarized edge states in TlGaS2 nanoribbons

We have investigated TlGaS 2 single-layer and TlGaS 2 nanoribbons using density functional theory (DFT). Phonon dispersion curves calculated within the density functional perturbation theory indicate that the TlGaS 2 single-layer is dynamically stable. Starting from optimized TlGaS 2 single-layers, unterminated and terminated ribbon morphologies with varying edge Tl coverages were constructed. In order to account for the weak interaction between Tl and S atoms, van der Waals correction to DFT was employed. The electronic and magnetic structures of TlGaS 2 ribbons are modulated by the edge morphology. Dangling bond, non-bonding, and free-electron-like edge states are formed. The ribbons have metallic conduction channels stemming from parabolic bands crossing the Fermi level. The edge states appearing in the fundamental energy gap induce spin polarization at the edges. The TlGaS 2 nanoribbons provide two magnetic conduction channels along the Tl chains, and thus the nanoribbon acts as two magnetic nanowires. • It is possible to reach the single-layer limit in TlGaS 2 ultrathin. • The single-layer TlGaS 2 is semiconducting with a larger bandgap than bulk. • Parabolic bands appear in the electronic structure of TlGaS 2 nanoribbons due to the edge states. • The edge states in TlGaS 2 nanoribbons provide spin-polarized metallic conduction channels.