First-principles Study On Magnetic Manipulation Of Black Phosphorene Nanoribbons

Due to natural direct band gap structure,relatively high on/off switching ratio,charge carrier mobility,and strong intrinsic in-plane anisotropy,black phosphorene has quickly become a hot material in the field of condensed matter physics.Since the unique quantum confinement and edge effects,two-dimensionally etched or patterned one-dimensional nanoribbons provide greater electronic tenability,allowing us to gain sufficient flexibility in the functional design and optimization of the device.Therefore,we urgently need to understand the properties and functional design methods of black phosphorus nanoribbons in order to bring possible applications to the next generation of nanoelectronic devices,paving the way for the development of spintronics.In this paper,the first-principles method is used to study the magnetic induction of hydrogenated Zigzag and Armchair-type phosphorene nanoribbons under the adsorption of transition metal atoms,and 5% uniaxial strain is applied to modulate the magnetic properties of the nanoribbons.The main contents and results are as follows:In chapter 1,we briefly outline the low-dimensional nanomaterials,mainly the basic structure,specific properties and broad application prospects of the low-dimensional black phosphorus materials.And discuss the structure and properties of the two types of nanoribbons derived from black phosphorene.We then survey the magnetic manipulation methods of nanomaterials are mentioned.Adsorption or substitutional doping of transition metal(TM)atoms on phosphorene is regarded as an effective approach to induce magnetization of nanomaterials with large Curie temperature.Therefore,it is proposed to study the possibility of the magnetic induction of non-magnetic black phosphorene nanoribbons by adsorbing 3d transition metal atoms on black phosphorene nanoribbons,and the ability to modulate the magnetism of the system by applying strain.In chapter 2,we introduce the first-principles density functional theory(DFT)method widely used in the field of condensed matter physics,computing science,and materials science.And it mainly introduces the density functional theory used in the calculation.At the same time,the simulation calculation software packages,modeling software and post-processing data processing and mapping software used in the calculation process are mentioned.In chapter 3,we first establish the structure models of Zigzag and Armchair type black phosphorene nanoribbons.And DFT calculations is used to study the magnetic ordering and electronic properties of 3d transition metal atoms adsorbed on black phosphorene nanoribbons.The results show that the edge-hydrogenated black phosphorene nanoribbons are all non-magnetic direct band gap semiconductors,and their electronic structures are obvious anisotropic.The transition metal atoms(Sc,Ti,V,Cr,Mn,Co)are the most stably adsorbed on the hollow site of black phosphorene nanoribbons and produce local magnetic moments,which do not significantly change the geometry of the black phosphorene nanoribbons.There are significant differences in the local magnetic moments produced,and the magnitude of the coupling magnetic moment depends on the type of transition metal atoms.This can be explained by crystal field theory that the crystal field of black phosphorus nanoribbons and the strong exchange interaction of transition metal adatoms induce the splitting of 3d orbitals of adatoms.Finally,the electronic structure of black phosphorene nanoribbon systems adsorbed the transition metal atoms is investigated.The transition metal adatoms bring the new states within the band gap of the intrinsic black phosphorus nanoribbon,so that the band gap of the systems is significantly narrower,but still exhibit semiconductor behavior.In chapter 4,the strain effects,5% tensile and compressive strain,on the adsorption energies,magnetic ordering and electronic properties of 3d transition metal atoms adsorbed on the black phosphorene nanoribbons are studied.It is found that the adsorption of Sc,Ti,V,Cr,Mn,Fe and Co atoms on the black phosphorene nanoribbons is more stable by 5% compressive strain,containing zigzag and armchair types.In addition,the strain can significantly modify the local magnetic moment and magnetic coupling state of some TM adatomic systems,causing the transition from magnetic antiferromagnetic(AFM)to ferromagnetic(FM)coupling state.We observe the electronic structure of the black phosphorene nanoribbon system significantly changed by applying strain,and even caused the electronic structure of Sc@ZBPNR system a transfer from semiconductor to metallic character.Chapter 5,we provide a summary and outlook.