Hole doping at Sn sublattice of the buckled honeycomb SnX (X = S and Se) monolayer: an efficient functionalization approach

Abstract

In this work, hole doping at the Sn sublattice is explored to induce feature-rich electronic and magnetic properties in SnX (X = S and Se) monolayers. In the buckled honeycomb structure, SnX monolayers exhibit good dynamical and thermal stability. Calculations indicate the non-magnetic semiconductor nature of SnS and SnSe monolayers with energy gaps of 2.31(3.01) and 2.21(2.88) eV, respectively, obtained using the PBE(HSE06) functional. A single Sn vacancy results in the emergence of half-metallicity with a total magnetic moment of 2.00, where the X atoms closest to the defect site mainly produce the magnetic properties. Similarly, the half-metallic nature is induced by doping with IA-group (Li and Na) atoms, however the magnetization is weaker with total magnetic moments between 0.95 and 1.00 μ_B. Herein, the magnetism is originated mainly from the p orbitals of chalcogen X atoms closest to the doping site. On the other hand, magnetic semiconductor nature emerges as a consequence of incorporating IIIA-group (Ga and In atoms) impurities. In these cases, a total magnetic moment of 1.00 μ_B is obtained, where impurities and their neighbor atoms play a key role in the monolayer magnetization. The density of states spectra and Bader charge analysis indicate ionic chemical bonds between Li(Na) atoms and X atoms, while the Ga(In)–X chemical bonds are a mix of covalent and ionic characters. The results presented herein may introduce the defected and doped SnX monolayers as prospective two-dimensional (2D) spintronic materials, such that hole doping can be considered as an efficient approach to functionalize SnX monolayers.