原子吸附的二维CrI_(3)铁磁半导体电学和磁学性质的第一性原理研究

First principles study of electrical and magnetic properties of two-dimensional ferromagnetic semiconductors CrI_(3) adsorbed by atoms

采用第一性原理的方法系统研究了碱(土)金属原子、过渡金属原子和非金属原子吸附的二维CrI_(3)单层的电学和磁学性质.结果表明,金属原子倾向于吸附在6个I原子形成的环中心并且与Cr原子处于同一高度,非金属原子吸附在I原子形成的环内,但位置则依赖于原子种类.除Ti和Mn原子之外的其他原子的吸附并未改变CrI_(3)单层的本征铁磁半导体属性,而Ti和Mn原子的吸附则使CrI_(3)单层转变为反铁磁构型.金属原子的吸附导致Cr原子局域磁矩增加,但不超过4μ_(B);而非金属原子的吸附则使Cr原子的局域磁矩呈现多样化.结合分波态密度我们对Cr局域磁矩的变化机制进行了细致分析,发现Cr磁矩的增加与电荷转移直接相关.我们的研究结果为铁磁半导体CrI_(3)的性能调控提供了新的思路,在未来自旋电子学中有着潜在的应用前景.

Recent experimental discovery of intrinsic ferromagnetism(FM)in chromium triiodide (CrI_(3)) monolayer opens a new way to low-dimensional spintronics.Two-dimensional(2D)CrI_(3) monolayer is of great significance for its magnetic and electronic properties.Generally,surface atomic adsorption is an effective way to modify the physical properties of layered magnetic materials.Here in this work,we use the first-principles method based on density functional theory(DFT)to systematically study the electronic structure and magnetic properties of 2D CrI_(3) monolayers that have adsorbed other metal atoms(specifically,alkali(alkaline earth)metal(Li,K and Mg),transition metal(Ti,V,Mn,Fe,Co and Ni)and non-metal(N,P,O and S)atoms).Our results show that the metal atoms tend to be adsorbed in the center of the ring formed by the six I atoms and stay at the same height as Cr atoms,while the positions of the optimized non-metal atoms are in the ring formed by the six I atoms and depend on the type of the atoms.The adsorption of atoms(except for Ti and Mn atoms)does not change the intrinsic ferromagnetic semiconducting properties of CrI_(3) monolayer.The CrI_(3) monolayers with Ti or Mn adsorption are antiferromagnetic semiconductors.Moreover,we find that the adsorption of different atoms regulates the local magnetic moments of Cr atoms.The adsorption of metal atoms increases the local magnetic moments of Cr atoms,but not exceeding 4μB.However,the adsorption of non-metallic atoms makes the local magnetic moments of Cr atoms diversified.The adsorption of O and N atoms retain the local magnetic moment of Cr atoms,while the adsorption of P and S atoms increase the local magnetic moment.By combining the projected density of states,we analyze in detail the local magnetic moments of Cr atoms.The increase of the local magnetic moments of Cr atoms is directly related to the charges transferring.Our results provide new ideas for regulating the performance of the magnetism of 2D intrinsic ferromagnetic semiconductor CrI_(3),which will have potential applications in the spintronics in the future.