Fig. 1. Geometry of alkali and alkali-earth metals doped GaN monolayer: (a) Top view; (b) side view.碱金属和碱土金属掺杂GaN单层结构图　(a) 俯视图; (b) 侧视图

Fig. 2. Spin charge density distributions of single atom doped GaN monolayer, isosurface is 0.004 eV/Å: (a) Li doping; (b) Na doping; (c) K doping; (d) Rb doping; (e) Be doping; (f) Mg doping; (g) Sr doping.单原子掺杂GaN单层的自旋电荷密度分布图, 等值面为0.004 eV/Å　(a) Li掺杂; (b) Na掺杂; (c) K掺杂; (d) Rb掺杂; (e) Be掺杂; (f) Mg掺杂; (g) Sr掺杂

Fig. 3. Spin resolved total DOS and PDOS of GaN monolayer doped single-atom: (a) Pristine; (b) Li doping; (c) Na doping; (d) K doping; (e) Rb doping; (f) Be doping; (g) Mg doping; (h) Sr doping.单原子掺杂GaN单层的自旋DOS和PDOS图　(a) 未掺杂; (b) Li掺杂; (c) Na掺杂; (d) K掺杂; (e) Rb掺杂; (f) Be掺杂; (g) Mg掺杂; (h) Sr掺杂

Fig. 4. Band structures for single atom doped GaN monolayer, the blue and the red respectively represent the spin up and the spin down: (a) Pristine; (b) Li doping; (c) Na doping; (d) K doping; (e) Rb doping; (f) Be doping; (g) Mg doping; (h) Sr doping.单原子掺杂GaN单层的能带结构, 图中蓝与红分别代表自旋向上与向下　(a) 未掺杂; (b) Li掺杂; (c) Na掺杂; (d) K掺杂; (e) Rb掺杂; (f) Be掺杂; (g) Mg掺杂; (h) Sr掺杂

Fig. 5. (a) Top and side views of a local structure centered on the nearest neighboring N atom of the doped atom; (b) schematic diagram of the energy-level splitting and electron filling of the nearest N atom of the Li, Be-doped atom.(a) 掺杂原子最近邻N原子为中心的局部结构俯视图和侧视图; (b) Li, Be掺杂原子最近邻N原子能级劈裂及电子填充示意图

Fig. 6. The p-orbital DOSs of the nearest neighbor N atom of doped atom: (a) Pristine; (b) Li doping; (c) Na doping; (d) K doping; (e) Rb doping; (f) Be doping; (g) Mg doping; (h) Sr doping.掺杂原子最近邻N原子的p轨道态密度图　(a) 未掺杂; (b) Li掺杂; (c) Na掺杂; (d) K掺杂; (e) Rb掺杂; (f) Be掺杂; (g) Mg掺杂; (h) Sr掺杂

Fig. 7. (a) Spin charge density distribution of the Mg-doped C4 configuration, the isosurface is 0.02 eV/Å; (b) PDOS of Mg-2p, 1N-2p, 2N-2p and 3N-2p in the Mg-doped C4 configuration.(a) Mg掺杂C4构型的自旋电荷密度分布图, 等值面为0.02 eV/Å; (b) Mg掺杂C4构型中Mg-2p, 1N-2p, 2N-2p和3N-2p的PDOS

Table 1. Energy difference , distance from the doped atom to the GaN monolayer , optimized M—N bond length d_M—N, formation energy of doped system , magnetic moment of the nearest three N atoms around the doped atom and total magnetic moment of doped system . 两种掺杂模式的能量差 , M原子到GaN单层的距离 , 优化后M—N键长d_M—N, 体系形成能 , 三个最近邻N原子磁矩 和体系总磁矩

Table 2. Distance between the two doped atoms after structural optimization , relative stability of the four configurations , energy difference between AFM and FM , total magnetic moment of doped system , coupling is the magnetic coupling of various configurations of double M atom doped GaN monolayer. 结构优化后两掺杂原子的距离 , 4种构型相对稳定能 , AFM与FM的能量差 , 掺杂体系总磁矩 , coupling为双M原子掺杂的GaN纳米片各构型的磁耦合态