The Modulation Of 3d Transition Metal ? Doping And Extended Defects On The Magnetic Properties Of Monolayer MoS₂

Since the discovery of graphene in 2004,the research upsurge of graphene has been raised due to its excellent electronic and mechanical properties.However,graphene has no bandgap,which hampers its application in semiconductor devices.Later,it was devoted to the research of like-graphene systems with wide bandgap.For example,single-layer hexagonal boron nitride?BN?,single-layer molybdenum disulfide?MoS₂?,phosphorene have been widely studied in recent years.Monolayer MoS₂ is a direct band gap semiconductor with 1.8eV bandgap,and single-layer MoS₂ transistors exhibit very high current on/off ratio and high mobility at room temperature.After that,in order to meet the practical needs of semiconductor devices,many methods have been explored to modulate the electronic properties of monolayer MoS₂.The most common methods are doping,adsorbing with foreign atoms,and applying external strain,electric field,and so on.In this paper,based on first principles calculation,the magnetic and electronic properties of the single Cr or Fe doped monolayer MoS₂ are studied.The results have shown that the two doped systems are narrow bandgap semiconductors,and the doped Cr and Fe form the local states in the band gap,resulting in the bandgap reduced.Moreover,Cr doped monolayer MoS₂ shows zero magnetism,while Fe doped system has 2?B total magnetic moment.Subsequently,we study the Cr and Fe ?-type doped monolayer MoS₂,where four configurations are considered,and we found that ?-type magnetic chains greatly affect the intrinsic properties of the systems.The nature of the four configurations are as follows: FeFe-chain-MoS₂ is ferromagnetic half-metal,CrCr-chain-MoS₂ is antiferromagnetic semiconductor,FeFeCrCr-chain-MoS₂ is antiferromagnetic metal,and CrFe-chain-MoS₂ behaves as a ferrimagnetic half-metal.The half-metallic of CrFe-chain-MoS₂ is mainly attributed to the states of the doped Fe atom near the Fermi energy.Moreover,Cr and Fe are antiferromagnetic coupling through the medium of middle S atom,and which follows GKA rules.The existence of line defects would change the original structures,resulting in the change of a series of properties.Here,we study the effect of line defects of monolayer MoS₂ on the electronic structures.Because the existence of the line defects destroys the complete periodicity of the original structure,we construct a model containing two kinds of line defects.It not only can ensure the complete periodic structures,but also achieve to study simultaneously two kinds of line defects: LD-I and LD-II.The results show that the local states formed by two kinds of line defects fill in the band gap,resulting in metallic property of the systems.Therefore,the line defects may be an effective method to construct one-dimensional conductive channel.To modulate the magnetic properties of the one-dimensional conductive channel,we try to control their electronic structures by adsorbing TM?V/Cr/Mn/Fe/Co?on the line defects.The adsorption energies of the systems indicate that the adsorption energies of TM chain on the LD-I are much higher than that of single TM atoms adsorbing,which indicates the adsorption of TM chain on LD-I are very stable.The calculation results show that five doped systems are induced to be magnetic,Mn/Fe/Co doped systems are all metal,and V/Cr behaves as half-metal,which provide a preferred base material for spintronics.