Effect Of Vacancy And Transitiom Metal Dopimg On Magnetic Properties Of 3C-SiC Nanow Res

With the rise of semiconductor spintronics,dilute magnetic semiconductors have became a hot topic of research.The key issue of current research is to find dilute magnetic semiconductor materials with high spin polarization and high Curie temperature.As a potential dilute magnetic semiconductor material,3C.-SiC nanowires already possess room temperature ferromagnetism in experiments,but the study on the microscopic mechanism of room temperature ferromagnetism is still relatively rare.The ferromagnetic state of 3C-SiC nanowires may be related to vacancies,doping impurities and other factors.Therefore,we use the first principles calculation method to study the electronic structure and magnetic properties of intrinsic 3C-SiC nanowires,3C-SiC nanowires with Si vacancy or Si-C double vacancies in different valence states,3C-SiC nanowires doped by different transition metal(TM)impurity,3C.-SiC nanowires doped by different Mn concentrations,3C-SiC nanowires co-doped by vacancy and different transition metal imparity from the formation energy,hand structure,density of states,spin density and Mulliken population.The main conclusions are as follow:1.Intrinsic 3C-SiC nanowires are non-magnetic.The 3C-SiC nanowires with neutral Si vacancy and Si-C double vacancies are non-magnetic,while 3C-SiC nanowires with negative valence Si vacancies and Si-C double vacancies arc magnetic.From the density of' states analysis,the source of the magnetic is the spin splitting of the C-2p state.The magnetic moments of nanowires with negative monovalent Si vacancies,negative divalent.Si vacancies,and negative monovalent Si-C double vacancies are 2uB,3uB and 1uB,respectively.3C-SiC nanowires with negative monovalent Si vacanc.ies and negative monovalent Si-C.double vacancies are antiferromagncticaliy stable,while the 3 C-SiC nanowire with negative divalent Si vacancies may maintain a stable ferromagnetic state at room temperature.2.In diffcrent transition metal(Fe,V,Cr,Mn)doped 3C-Si36TMC37 nanowires,the Fe-doped nanowire possess metal properties and are non-magnetic,while V,Cr and Mn doped nanowires are all half-metal materials and magnetic.The magnetic moments are 1uB,2uB and 3uB,respectively,and the nanowires are all ferromagnetically stable.From the density of states analysis,the magnetic originate from the hybridization of TM-3d states and C-2p states.Among them,Cr-doped 3C-SiC nanowire possess the largest half-metal band gap and the highest Curie temperature,so it can be a good half-metallic ferromagnet.In addition,the magnetic properties of 3C-SiC nanowires doped by different Mn concentrations were discussed.With the increase of Mn concentration,the degree of spin splitting in C-2p state and Mn-3d state increases,and the total magnetic moment of nanowire also increases.3.In vacancy and different transition metal co-doped 3C-SiC nanowires,3C-Si36FeC36 nanowire,3C-Si36VC36 nanowire,3C-Si36CrC36 nanowire,3C-Si36MnC36 nanowire are all magnetic,and the magnetic moments are 4uB 1uB,4uB and 5UB,respectively.From the density of states analysis,the magnetic originate from the hybridization of TM-3d states,C-2p states and Si-3p states.Among them,3 C-Si36FeC36 nanowire and 3C-Si36VC36 nanowire possess metal properties and are antiferromagnetically stable,while the 3C-Si36CrC36 nanowire and 3C-Si36MnC36 nanowire are half-metallic materials and are ferromagnetically stable,Compared with 3C-Si36CrC37 nanowire and 3C-Si36MnC37 nanowire,the half-metal band gap and Curie temperature of 3 C-Si36CrC36 nanowire and 3C-Si36MnC36 nanowire are reduced.