ZnO1-xCx稀磁半导体的磁特性的第一性原理和蒙特卡罗研究

利用第一性原理计算得到C掺杂ZnO的电子结构，发现系统具有半金属的电子结构.从态密度的分析可以看到Zn-3d和C-2p电子具有强烈的杂化作用，这是体系具有相对稳定铁磁基态的原因.利用第一性原理得到的磁性耦合强度并结合蒙特卡罗模拟得到了C掺杂浓度为555%，833%，125%的ZnO_1-xC_x分别具有210 K，260 K，690 K的居里温度.同时，详细地分析了C掺杂引起的电子转移和C，Zn，O的s，p和d电子的自旋向上和自旋向下电子数的变化.通过比较研究，发现ZnO_1-xC_x的局域磁矩主要来源于Zn-3d 电子和C-2p 电子之间的相互作用，而局域磁矩耦合倾向于RKKY耦合. 关键词： 1-xC_x')" href="#">ZnO_1-xC_x 磁性 第一性原理 蒙特卡罗模拟

Ferromagnetism of C doped ZnO: first-principles calculation and Monte Carlo simulation

In this work, the electronic structure and the stability of ferromagnetism of C-doped ZnO are studied by first-principles calculations and Monte Carlo simulation. The calculated results indicate that the ferromagnetic ground state is stabilized by its half-metallic electronic structure which originates from the strong hybridization between Zn-3d and C-2p electrons. Meanwhile, by using the coupling strength obtained from first-principles calculations and Monte Carlo method, the Curie temperatures of ZnO_1-xC_x （x=555%, 833% and 125%） are predicted to be 210, 260 and 690 K, respectively, which is generally consistent with theroetical and experimental results. The electronic transfer resulting from C doping, and the changes between spin-up and spin-down electron changes for s, p and d electrons of C, Zn, O atom are analyed in detail. The simulated results show that, the local magnetic moments of ZnO_1-xC_x originate mainly from the hybridization interaction between Zn-3d and C-2p electrons, while the magnetic coupling between the local magnetic moments is preferentially the RKKY coupling.