First-principles Study Of Janus MoSSe

Janus MoSSe is a new two-dimensional(2D)material that has attracted widespread attention due to its interesting tunable electronic and optical properties.In particular,such 2D structure has been successfully synthesized by various experimental strategies.In this thesis,we,using density functional theory(DFT)and first-principles calculations based on spin-polarization,investigate the geometry,electronic and magnetic properties of the monolayer(ML)and bilayer(BL)Janus MoSSe doping 3d transition metal(TM)atoms.Firstly,we study the geometry,energy and magnetic properties,and electronic properties of ML Janus MoSSe with five kinds of TM atoms(Cr,Mn,Fe,Co and Ni)doped and adsorbed on its surface.The results show that the geometry of ML Janus MoSSe can be well preserved after doping and absorbing the TM atoms.In addition,TM atoms can also be well coupled with the ML Janus MoSSe structure.Interestingly,we have also found that these five TM atoms can make the nonmagnetic ML Janus MoSSe system exhibit magnetic properties for the doped system.However,only four TM atoms(Cr,Mn,Fe and Co)can make the ML Janus MoSSe system exhibit magnetic properties for the adsorpted system.In addition,the TM atoms doped and absorded on the surface of ML Janus MoSSe can also effectively modulate its electronic properties.It is shown that ML Janus MoSSe system can be a half-metal,metal or spin-polarized semiconductor depending on the type of dopant atoms.The results show that TM atoms can modulate the electronic structure of ML Janus MoSSe and introduce magnetic moment into the system.The system of ML Janus MoSSe with TM atoms doped and adsorbed on its surface can be potential candidates for spintronics and optoelectronics.In addition,we continue to study the geometry,energy and magnetic properties,and electronic properties of BL Janus MoSSe with five kinds of TM atoms(Ti,Cr,Mn,Fe and Ni)adsorbed on its interlayer.The results show that the structure of BL Janus MoSSe can be well kept after adsorption of TM atoms,indicating that TM atoms do not destroy the stability of BL Janus MoSSe structure.The TM atoms can also be well matched with S and Se atoms in BL Janus MoSSe structure.Furthermore,we find that the total magnetic moment of the four absorbed systems and local magnetic moment of the four TM atoms are not zero,except for the Ni absorbed system.There is no magnetism in the Ni absorbed system and the other TM atoms absorbed system can exhibit magnetic properties.The TM atoms adsorbed on interlayer can also effectively functionalize the electronic properties of BL Janus MoSSe.The calculation results show that the Ti-adsorbed system exhibits half-metallic properties.In contrast,the Cr-?Mn-?Fe-and Ni-adsorbed systems retain the inherent semiconductor properties of BL Janus MoSSe.Therefore,the TM atoms-adsorbed BL Janus MoSSe systems may be useful for the applications of spintronics and magnetic storage.