Doping-Induced Magnetism and Half-Metallicity in Nanoribbons of Quartic Dispersion Materials

Abstract

Two-dimensional (2D) quartic dispersion materials are known to develop magnetization upon doping. Here, we conduct a systematic investigation of magnetization in hole-doped quartic dispersion materials (GaS, InSe, TiO2), focusing on the effects of structural confinement from 2D monolayers to quasi-one-dimensional nanoribbons (NRs). Upon hole doping, these NRs develop itinerant magnetization across a broad range of carrier densities and display half-metallic behavior. At higher doping rates, strong deformation of the topmost valence bands occurs in addition to spin splitting. The spin-polarization energies (Esp) of these NRs enhance remarkably relative to their 2D counterparts, with maximum increase being in the case of TiO2 from 31 to 101 meV/carrier. The Esp strongly depends on the degree of localization of the magnetic moments along the width of NRs, which is determined by edge passivation and ribbon width.