论文标题
氧化Ca的结构过渡$ _2 $ N选举：CAO/CAN 2D异质结构
Structural Transition in Oxidized Ca$_2$N Electrenes: CaO/CaN 2D heterostructures
论文作者
论文摘要
基于第一原理计算，我们表明Ca $ _2 $ n电气的超薄薄膜的氧化，epletrenes，驱动六角形$ \ rightarrow $ torgagonal结构过渡。可以将氧化单层（ML）和双层（BL）系统的基态配置视为CAO/CAN和CAO/（CAN）$ _ 2 $/CAO二维（2D）异质结构。在这两个系统中，我们都发现位于真空水平附近的几乎游离电子（NFE）状态，空间投影揭示它们位于氧化的CAO表面上方。着重于磁性特性，我们发现氧化Ca $ _2 $ N的氮原子变成了自旋偏振（$ \ sim $ 1 $μ__ {\ rm B} $/n-atom）; （i）在ML系统中，（ii）（ii）在CAO/（CAN）$ _ 2 $/CAO中，（ii）对铁磁相的精力充沛的偏好，而（ii）（ii）（ii）（ii）（ii）（ii）（ii），（ii）有能量偏好。我们表明，在机械压缩时可以增强这种FM偏好。进一步的电子结构计算表明，FM CAO/CA $ _2 $ n/caO提出了半金属性，其中金属通道项目（主要是）在n- $ 2p_ {x，y} $ orbitals上。除了总能量结果外，还进行了分子动力子和声子光谱计算，以验证其热和结构稳定性。这些发现表明，CAO/CA $ _2 $ n/caO是一个非常有趣的，结构稳定的2D FM异质结构，表征了半金属乐队，夹在氧化表面上的NFE状态。
Based on first-principles calculations we show that the oxidation of ultrathin films of Ca$_2$N electrides, electrenes, drives a hexagonal$\rightarrow$tetragonal structural transition. The ground state configuration of the oxidized monolayer (ML) and bilayer (BL) systems can be viewed as CaO/CaN and CaO/(CaN)$_2$/CaO two dimensional (2D) heterostructures. In both systems, we found nearly free electron (NFE) states lying near the vacuum level, and the spatial projection reveals that they are localized above the oxidized CaO surface. Focusing on the magnetic properties, we find that the nitrogen atoms of the oxidized Ca$_2$N becomes spin-polarized ($\sim$1 $μ_{\rm B}$/N-atom); where (i) the ferromagnetic and the anti-ferromagnetic phases are nearly degenerated in the ML system, CaO/CaN, while (ii) there is an energetic preference for the ferromagnetic phase in CaO/(CaN)$_2$/CaO. We show that such a FM preference can be strengthened upon mechanical compression. Further electronic structure calculations reveal that the FM CaO/Ca$_2$N/CaO presents half-metallicity, where the metallic channels project (predominantly) on the N-$2p_{x,y}$ orbitals. In addition to the total energy results, molecular dynamic and phonon spectra calculations have been done in order to verify its thermal and structural stabilities. Those findings suggest that CaO/Ca$_2$N/CaO is a quite interesting, and structurally stable, 2D FM heterostructure characterized half-metallic bands sandwiched by NFE states lying on the oxidized surfaces.
