Electronic and magnetic properties of Janus Al2SO Janus monolayer modified by defects and doping: A first-principles study

Abstract

In recent years, two-dimensional (2D) Janus structures have attracted great research attention because of their promise for practical applications. In this work, Janus monolayer Al2SO under eects of vacancy and doping is systematically investigated. Pristine Al2SO monolayer exhibits the direct-gap semiconductor nature with a band gap of 1.52 eV. The chemical bonds Al1-O and Al2-S are predominantly ionic, meanwhile the covalent character dominates Al1-Al2 bond. Single Al2 vacancy induces the half-metallic nature with a total magnetic moment of 1.00 B , meanwhile no magnetism is obtained by creating single Al1 vacancy that metallizes the monolayer. The nonmagnetic semiconductor nature is preserved with single O and S vacancies, which tune the band gap to 1.41 and 1.70 eV, respectively. Signicant magnetism with an overall magnetic moment of 5.00 B is induced by doping with single Fe atom. Our simulations assert the antiferromagnetic semiconductor nature of Fe-doped Al2SO monolayer, where the antiferromagnetism is most stable in the case of pair-Fe-atoms substitution with an energy dierence of 309.3 meV compared to the ferromagnetism. Beyond monoelement doping, the substitution of small clusters FeN3 and FeF3 is also investigated. These clusters induce feature-rich electronic natures with total magnetic moments of 2.00 and 2.11 B , respectively. In all cases, Fe atoms originate mainly the system magnetic moment.Small cluster doping also generates multiple mid-gap energy states around the Fermi level, which is crucial to control the system electronic nature.Our study provide new insights into the functionalization of Janus monolayer Al2SO that could be employed to make new promising 2D spintronic materials.