First-principles Study Of Magnetic Anisotropy And Curie Temperaturein CrSI Monolayer

Exploring the room temperature intrinsic ferromagnetic two-dimensional（2D）semiconductor materials with large vertical magnetic anisotropy has important practical significance for the development of high-performance ultra-thin semiconductor spintronic devices.Most of the existing studies focus on the Curie temperature（T_C）control of materials with large vertical magnetic anisotropy.However,due to the complexity of the material itself,the control means to make its T_Cclose to room temperature are still limited.At present,the 2D intrinsic ferromagnetic semiconductor at room temperature has not been prepared experimentally.Based on the current research status,we will"go the other way",take the system with higher T_Cas the research object,explore and study the regulation of its magnetic anisotropy,and then realize the expansion of 2D intrinsic ferromagnetic semiconductor with both larger vertical magnetic anisotropy and higher T_C.Monolayer Cr XY（X=O/S/Se;Y=F/Cl/Br/I）,as an important branch of 2D intrinsic ferromagnetic semiconductor materials,shows unique advantages in T_C,and monolayer Cr SBr has been successfully prepared in experiments.However,the small magnetic anisotropy energy and in-plane orientation of the easily magnetized axis of this kind of materials are not conducive to the improvement of thermal stability and storage density of spintronic devices and the reduction of energy consumption.Therefore,we combined first-principles calculation and Monte Carlo simulation to study the transition metal V and Mn doped monolayer Cr SI,and systematically studied the electronic structure,magnetic properties and T_Cof the doped system.The results of formation energy,phonon dispersion,ab initio molecular dynamics simulation and elastic constant calculation show that the monolayer Cr VS₂I₂and monolayer Cr Mn S₂I₂are stable.More importantly,V and Mn doping can effectively control the magnetization direction of monolayer Cr SI.The monolayer Cr VS₂I₂and Cr Mn S₂I₂systems have been significantly enhanced,and their values have increased from 0.001 me V/atom to 0.997 me V/atom and 1.434 me V/atom,respectively.Interestingly,the T_Cof monolayer Cr VS₂I₂and Cr Mn S₂I₂systems has also been further improved,from 175 K to 352 K and 312 K respectively.In addition,monolayer Cr VS₂I₂still retains the properties of semiconductor,with a direct band gap of 0.38 e V,while monolayer Cr Mn S₂I₂is converted into semi-metallic ferromagnet.Our work provide a promising way to realize 2D intrinsic ferromagnetic semiconductor materials and semi-metallic materials with high T_Cand large vertical magnetic anisotropy.