Searching for new two-dimensional spintronic materials: Doping-induced magnetism in graphene-like SrS monolayer

Abstract

In this work, doping approach is explored to induce feature-rich electronic and magnetic properties in graphene-like SrS monolayer and make it prospective spintronic two-dimensional (2D) candidate. For such goal, $3d$ transition metals (V, Cr, Mn, and Fe) and halogens (F, Cl, Br, and I) are selected as dopants at Sr and S sublattice, respectively. Pristine SrS single layer shows good dynamical and thermal stability. Its indirect-gap semiconductor nature is also asserted with energy gap of 2.87/3.81 eV obtained by PBE/HSE06 functional, generated by the separation in energy between S-$3p$ and Sr-$4d$ orbitals. The magnetic semiconducting with total magnetic moment of 2.00 ${\mu }_B$ is obtained by creating a single Sr vacancy, meanwhile S single vacancy preserves the non-magnetic nature. The monolayer is significantly magnetized by doping with transition metals, where large total magnetic moments of 3.00, 4.00, and 5.00 ${\mu }_B$ are obtained for the V-, Cr/Fe-, and Mn-doped SrS monolayer, respectively. In these cases, impurities play a key role on producing magnetic properties and generating the magnetic semiconductor nature. This feature-rich nature is also induced by doping with F atom, where a total magnetic moment of 1.00 ${\mu }_B$ is obtained that is originated mainly from Sr atoms closest to the doping site. Besides, Cl doping leads to the emergence of the half-metallicity. Importantly, the magnetization becomes significantly weaker according to increase the atomic number of halogen dopants, such that the non-magnetic nature is preserved by doping with I atom. This feature is attributed to the increase of the electronic hybridization. Results presented herein introduce the doped SrS monolayer as promising 2D spintronic materials, exhibiting novel properties that are not found in the pristine counterpart.