碱金属(Li、Na、K)掺杂二维单层CrI_(3)的半金属铁磁性研究  

Halfmetallic ferromagnetism study of alkali metal(Li,Na,K)doped two-dimensional CrI_(3) monolayer

作　　者：张伟华 李雨欣 王朕 骆逸夫 刘祥林 彭波 丁守兵 毋志民 ZHANG Weihua;LI Yuxin;WANG Zhen;LUO Yifu;LIU Xianglin;PENG Bo;DING Shoubing;WU Zhimin(Chongqing Key Laboratory of Photoelectric Functional Materials,College of Physics and Electronic Engineering,Chongqing Normal University,Chongqing 401331,China)

机构地区：[1]重庆师范大学物理与电子工程学院,光电功能材料重庆市重点实验室,重庆401331

出　　处：《功能材料》2024年第11期11101-11106,共6页Journal of Functional Materials

基　　金：重庆市教委科学技术研究计划项目(KJZD-K202300512);重庆市博士直通车项目(CSTB2022BSXM-JCX0092)。

摘　　要：基于第一性原理计算的方法,对二维单层CrI_(3)及碱金属(Li、Na、K)掺杂后的电荷布局、晶体稳定性、电子结构和居里温度进行了计算和分析。研究结果显示:在单层CrI_(3)和碱金属掺杂后,各原子之间的键合能力较强,体系表现出稳定的共价键晶体结构。在由I原子组成的八面体晶体场中,Cr原子发生自旋劈裂现象,使得单层CrI_(3)呈现磁性半导体性质。而碱金属的掺入增加了体系的载流子浓度,加强了Cr原子间的铁磁交换作用,使居里温度由46 K提高到95 K。此外,电子浓度的提升使得Cr-3 d轨道的电子占据数增加,导致Cr原子的自旋磁矩增大。这使得掺杂体系呈现稳定的半金属性,具有100%自旋极化率,并具备较大的半金属能隙,分别为1.13 eV(Li掺杂)、1.26 eV(Na掺杂)和1.41 eV(K掺杂),能有效抑制热扰动及自旋翻转,是自旋电子学领域的潜在候选材料。In recent years,two-dimensional(2D)magnetic materials have attracted considerable attention due to their excellent magneto-electric properties.By employing the first-principles calculations,the charge distribution,crystal stability,electronic structure,and Curie temperature(T C)of 2D CrI_(3) monolayer and its doping with alkali metals(Li,Na,K)were calculated and analyzed.The research results demonstrate that the CrI_(3) monolayer and alkali metal-doped systems exhibit stable covalent crystal structures,with strong bonding abilities between the atoms.Within the octahedral crystal field composed of I atoms,the Cr atoms undergo spin splitting,resulting in the magnetic semiconductor properties of the CrI_(3) monolayer.The introduction of alkali metals increases the carrier concentration of the system,thereby enhancing the ferromagnetic exchange interaction between Cr atoms and improving the T C from 46 K to 95 K.Furthermore,the increase in electron concentration leads to an increase in the occupancy of Cr-3 d orbitals,resulting in an enlargement of the spin magnetic moment of Cr atoms.This enables the doped system to exhibit stable half-metallicity,with a 100%spin polarization and a large half-metallic bandgap of 1.13 eV(Li doped),1.26 eV(Na doped)and 1.41 eV(K doped),respectively,effectively suppressing thermal disturbance and spin flipping.Therefore,these findings provide potential candidate materials for spintronics.

关 键 词：第一性原理计算 二维单层CrI_(3) 碱金属掺杂 居里温度 100%自旋极化率 

分 类 号：O469[理学—凝聚态物理] O472[理学—电子物理学]