高品质锰掺杂二维二硒化钼晶体的光与物质相互作用

Light-matter interactions in high quality manganesedoped two-dimensional molybdenum diselenide

最近,将磁性掺杂引入到二维硫族化合物中从而调控自旋电子学及谷电子学的研究引起了科学界的广泛关注.本文通过化学气相转移生长技术,实现了二硒化钼高达2.9%原子丰度的锰掺杂,并采用光谱学技术研究了晶体及解理的少层样品中光与物质相互作用.我们发现掺杂抑制了带电激子的发光,激子发光具有更长的时间寿命,同时面内E_(2g)^(2)和面外A_(1g)声子振动模式分别呈现出显著的蓝移和红移.此外,锰掺杂增强了能谷塞曼劈裂约50%,并保持了发光线偏振度对磁场的依赖关系.第一性原理计算显示,锰掺杂替代原子形成自旋极化的深能级,导致缺陷势场更倾向于捕获激子.锰掺杂降低了原子间的相互作用力常数,可以解释面外A_(1g)声子振动模式的红移.锰原子及最近邻的钼和硒原子带有显著的磁偶极,其交换作用影响了缺陷捕获的激子,从而增强了实验中观察到的g-因子.

Introducing magnetic dopants into twodimensional transition metal dichalcogenides has recently attracted considerable attention due to its promising applications in spintronics and valleytronics.Herein we realized manganese-doped molybdenum diselenide(MoSe_(2))single crystal via chemical vapor transport(CVT)reaction,containing up to 2.9%(atomic concentration)Mn dopants,and investigated the light-matter interaction in these samples.We observed a suppressed trion intensity,a longer photoluminescence lifetime,and prominent blue-and red-shift of E_(2g)^(2)(in-plane)and A_(1g)(out-of-plane)Raman modes,respectively.Moreover,the Mn dopants increase the valley Zeeman splitting of the MoSe_(2) monolayer by~50%,while preserving the linear dependence on magnetic field.First-principles calculations indicate that the spin-polarized deep level defect states are formed due to the Mn substitutional dopants in the Mo Se_(2) lattice.The resulting defect potential favors the funnelling of excitons towards the defects.The Mn dopants reduce the magnitude of the interatomic force constants,explaining the red-shift of the A_(1g)mode.The Mn atoms and their immediate Mo and Se neighbors carry significant magnetic moments,which enhance the observed exciton g-factors due to the exchange interactions affecting defect-bound excitons.