Magnetic Properties And Modulation Of Magnetism In Transition Metal Doped Low-Dimensional GeS Device

The 21st century is the golden period for the development and application of nanomaterials with the discovery and synthesis of various nanomaterials,which has accelerated the development of all kinds of the frontier field for science and technology.The graphene were discovered in 2004 makes the development and application of nanomaterials deep into the atomic scale.Many two dimensional materials,such as the single layer MoS2,monolayer BN and phosphorene,have been successfully synthesized in the experiment,and have been become the research object in many scientific research and application fields.The application of two-dimensional nanomaterials in the field of spintronics is one of hot topics in the frontier technology.While,lack of band gap for graphene,the low mobility for monolayer MoS2,the large band gap for single layer BN and the weak antioxidant of phosphorene limit their wide application.And these disadvantages can be surmounted for the two-dimensional GeS material.The 2D GeS is a phosphorene-like crystal material with a moderate band gap,higher carrier mobility,prominent anisotropy and other excellent properties.It is reported that the 2D GeS presents an excellent performance in the aspect of thermoelectric,photoelectric conversion and ferroelectric and so on Here,we focuse on the application of 2D GeS in the field of spintronics.It is found that the strong chemical interaction is occurred between the TM and GeS in both adsorption and substitution systems because of the sp3?like hybridization of the Ge and S atoms in the 2D GeS.The strong chemical interaction is conducive to limit the spreading of TM on the GeS surface and form the stable magnetic moment and modulate the magnetism.In application,the 2D GeS is superior to other 2D materials,such as graphene and MoS2 and so on.Therefore,the magnetic mechanism and magnetism modulation of 2D GeS doped by 3d transition metal(TM)are studied by using the first principles calculation basic on density functional theory(DFT)in our paper.And the research results are abtained as follows:(1)A nonmagnetic property is found in the Ni was adsorbing on the GeS surface,while integer magnetism was showed when Fe and Co adsorbing on the GeS surface,and their magnetic moments were 2?B and 1?B,respectively.Besides the magnetism of these adsorbed 2D GeS systems is verified by using the DFT+U method,and found that the magnetic properties are not affected by the U value when the Hubbard U is no more than 6 eV.It is found that the magnetism of TM adsorbed 2D GeS systems is mainly derived from the competition between the crystal field splitting and spin exchange splitting of TM-3d orbital based on the analysis of the spin polarization charge density distribution.(2)For the study of doped systems that Ge atom substituted by TM,the nonmagnetic property was showed only inNi@GeS system Meanwhile,the high spin states were showed in V@GeS,Cr@GeS,Mn@GeS,Fe@GeS and Co@GeS with the magnetic moment of 3?B,4?B,5?B,4?B,3?B,respectively.Besides the magnetism of these doped 2D GeS systems is verified by using the DFT+U method,and found that the magnetic properties are not affected by the U value when the Hubbard U is no more than 6eV.It is found that the magnetism of the transition metals doped systems mainly originate from the transition metal atoms by detailed analysis of spin charge density distribution and the splitting of TM-3d orbit.(3)Effective magnetic control is the key to the application of two-dimensional materials in spintronics.Therefore,the external electrical field was utilized to control the magnetism for TM doped 2D GeS.The transformation of TM@GeS between high and low spin states was showed found in our results,and the modulation of magnetism has been realized.The mechanism of magnetism modulation in external field is that the crystal field splitting is affected by EeXt and then the relative position of TM-3d orbital level si changed,which influence the spin configuration.Our results provide theoretical basis for the application of two-dimensional GeS in the spintronics,especially the magnetic memory.