Electronic Structure And Magnetic Properties Of Two-dimesion Cr-doped CdTe And ZnTe

The application of information technology provides convenience for operations in various fields such as military,aerospace,medical,etc.,and the spintronics theory has opened the prelude to the booming development of information technology.The advent of spintronics devices has promoted the innovation of information access technology.At present,the preparation process of spintronics devices is quite mature.The key is to find cheap and stable half-metallic magnetic materials.In the past,most of the materials used to prepare spin electronic devices were concentrated on traditional half-metallic bulk materials.The high storage speed requirements of big data operations made the development of new types of spin materials urgently.As a prototype of two-dimensional nanomaterials,graphene has been widely used in materials science with its unique structure and physical properties.The research on two-dimensional materials has covered the fields of semiconductors,half-metals,metals and topological insulators,but most of them are non-magnetic or dilute magnetic,and face great challenges in the practice of preparing nano-spintronics devices.Researchers have found that two-dimensional intrinsic half-metal materials are few and unstable,and they can be modified by adsorption,doping,and introducing defects.Transition metal-doped semiconductor single-layer structure is expected to achieve breakthroughs in new two-dimensional half-metallic materials,and they are potential applications in the field of spintronics.Density functional theory is based on quantum mechanics and has gotten by strict mathematical proof;it is currently a powerful tool for studying the electronic structure and physical properties of solid materials.It can not only predict the properties of unknown materials for reference,but also explore the microscopic mechanism of synthesized materials.In this paper,based on the first-principles calculation method of density functional theory,the electronic structure and magnetic properties of Cr-doped semiconductor CdTe and ZnTe single-layer films are studied in depth.We performed 4�4 supercells of CdTe and ZnTe single-layer structures,and used substitution doping model to replace Cd/Zn atoms in different positions of single-layer film structure with Cr atoms.The specific work content and conclusions include the following aspects:1.The geometrical parameters,formation energy and cohesive energy of the Cr-doped CdTe and ZnTe single-layer structure system were explored.The calculation show that the Cr-doped CdTe and ZnTe single-layer films with different doping configurations have good thermodynamic stability.2.The energy band structure,total state density?DOS?and partial wave state density?PDOS?of the original system and doped system of two-dimensional CdTe and ZnTe are analyzed.The results show that the electronic structures of these two films are very sensitive.Cr atom doping introduces a single spin polarization direction doped state into the band gap,the doped state appears metallic through the Fermi surface,and the band structure of the other spin direction has an obvious band gap This is a typical half-metal band structure.3.The total magnetic moment of the doped system and the local magnetic moment of the Cr atom are calculated.It is found that the original magnetic moment of the two-dimensional CdTe and ZnTe structures is almost zero,but the systems shows a weak ferromagnetic sequence.4.We calculated the exchange coupling constant and magnetization energy of the four Cr atoms doping systems,and ferromagnetic sequence and antiferromagnetic sequence of them are discussed.The Curie temperature of Cr₄Cd₁₂Te₁₆ and Cr₄Zn₁₂Te₁₆systems is predicted to be higher than room temperature according to the principle of average field approximation,indicating that this doped material is quite stable in magnetic properties.The main significance of our work is that a stable half-metallic magnetic material has been obtained by two-dimensional semiconductor doping.Compared with inherent half-metallic materials,doped half-metallic materials retain the stability of semiconductor materials,can ensure the stable operation of spintronic devices.It is a new half-metal materials source for making spintronics devices.