Anisotropic features in the electronic structure of the two-dimensional transition metal trichalcogenide TiS₃: electron doping and plasmons

Abstract

Analysis of the band structure of TiS3 single-layers suggests the possibility of changing their
\nphysical behaviour by injecting electron carriers. The anisotropy of the valence and conduction
\nbands is explained in terms of their complex orbital composition. The nature of the Fermi surface
\nand Lindhard response function for di erent doping concentrations is studied by means of rstprinciples
\nDFT calculations. It is suggested that for electron doping levels x (number of electrons
\nper unit cell) 0.18-0.30e the system could exhibit incommensurate charge or spin modulations
\nwhich, however, would keep the metallic state whereas systems doped with smaller x would be 2D
\nmetals without any electronic instability. The e ect of spin-orbit coupling in the band dispersion
\nis analysed. The DFT e ective masses are used to study the plasmon spectrum from an e ective
\nlow energy model. We nd that this material supports highly anisotropic plasmons, with opposite
\nanisotropy for the electron and hole bands.