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• The energy bands of Fe and Mn co-adsorbed monolayers of SnSe 2 exhibit semi-metallicity. • As tensile strain increases, the adsorption system transitions from semi-metallic to metallic, accompanied. • The co-adsorption system's curie temperature is calculated to be 205.2 K. • The application of Fe and Mn double transition metal atoms to monolayer SnSe 2 may have potential. Pure 2D SnSe 2 is not magnetic, which limits its application in spintronics. However, magnetic properties can be induced in pure 2D SnSe 2 by introducing transition metal elements. In this study, we used first-principles calculations based on density-functional theory to predict the electronic structure and magnetic properties of monolayer SnSe 2 under adsorption of Fe and Mn double transition metal atoms. Our findings show that the energy bands of Fe and Mn co-adsorbed monolayers of SnSe 2 exhibit semi-metallicity. As tensile strain increases, the adsorption system transitions from semi-metallic to metallic, accompanied by an increase in total magnetic moment. Based on the Heisenberg model, the co-adsorption system's Curie temperature is calculated to be 205.2 K. Our studies suggest that the application of Fe and Mn double transition metal atoms to monolayer SnSe 2 may have potential in spintronics. [ABSTRACT FROM AUTHOR]

Nowadays, two-dimensional materials are ideal for fabricating optoelectronic and spintronic devices. We have investigated the optical and magnetic properties of −6 % to 6 % strain on Mn-adsorbed monolayer SnSe 2 films using a first-principles approach. The Mn-adsorbed monolayer SnSe 2 is a magnetic semiconductor in the absence of strain effects. As the tensile strain increases, the band gap of the Mn-adsorbed monolayer SnSe 2 decreases and the structure becomes unstable, and Mn adsorption changes to exothermic adsorption at −6 % strain. The magnetic moment of the system increases slightly with increasing tensile strain and decreases rapidly when the strain reaches 4%. As the compressive strain increases, the magnetic moment first decreases slightly and then decreases rapidly when the strain reaches −4 %. Calculations of the optical properties show that the static dielectric constants at −6 %, −4 %, −2 %, 0 %, 2 %, 4 % and 6 % strains are 15.23, 10.19, 8.67, 7.78, 6.38, 5.99 and 5.92, respectively, which increase with increasing compressive strain. It decreases with increase in tensile strain. The static dielectric function increases as the compressive strain increases and decreases as the tensile strain increases. In the visible light region, the reflectivity, refractive index, extinction coefficient and photoconductivity in the XX and ZZ directions increase with increasing tensile strain. Our study shows that the optoelectronic and magnetic properties of the SnSe 2 adsorbed Mn system can be improved to some extent by applying strain, and this study is expected to provide theoretical guidance for the fabrication of SnSe 2 -based magnetic optoelectronic devices. [ABSTRACT FROM AUTHOR]