论文标题
真空环境中铜原子连接处的跳跃和电导高原形成的机制
Mechanisms of jump to contact and conductance plateau formation in copper atomic junctions in vacuum and aqueous environments
论文作者
论文摘要
通过第一原理理论和半经验计算，探索了水分子和单原子接触之间的相互作用，在铜原子连接的电导和机械力中所反映。我们研究铜电极的原子几何形状在存在和不存在水对电极彼此接近时的电导谱的情况下，在电导谱的情况下具有锥体和非结晶结构的影响。结果表明，纳米接触的原子布置对高原和电导值的形成具有至关重要的影响。在电极之间直接铜接触之前，氢键合的水分子桥接了连接电极。但是，单个H $ _ {2} $ o分子将两个铜电极的桥接仅发生在带有金字塔电极的连接处。我们的发现表明，H $ _ {2} $ o分子的存在强烈修饰了这些连接的电导曲线。在没有水分子的情况下，锥体连接在整数电导平台之间表现出连续的过渡，而在存在H $ _ {2} $ O分子的情况下，这些连接处的突然跳转到接触行为，没有明确定义的电导量。相比之下，在没有h $ _ {2} $ o分子的情况下，非结晶连接处显示跳跃到接触行为，没有定义明确的高原，而在H $ _ {2} $ O Molecules的存在下，它们会跳至触点和突然之间的分数和integer和integer和integer plateaus。
The interplay between groups of water molecules and single-atom contacts, as reflected in the electrical conductances and mechanical forces of copper atomic junctions, is explored by means of first-principles theory and semi-empirical calculations. We study the influence of the atomic geometries of copper electrodes with pyramidal and non-crystalline structures in the presence and absence of water on the conductance profiles as the electrodes approach each other. It is shown that the atomic arrangements of nano-contacts have crucial effects on the formation of plateaus and the conductance values. Groups of hydrogen bonded water molecules bridge the junction electrodes before a direct Cu-Cu contact between the electrodes is made. However, the bridging of the two copper electrodes by a single H$_{2}$O molecule only occurs in the junctions with pyramidal electrodes. Our findings reveal that the presence of H$_{2}$O molecules modifies strongly the conductance profile of these junctions. In the absence of water molecules, the pyramidal junctions exhibit continuous transitions between integer conductance plateaus, while in the presence of H$_{2}$O molecules, these junctions show abrupt jump to contact behavior and no well-defined conductance plateaus. By contrast, in the absence of H$_{2}$O molecules, the non-crystalline junctions display jump to contact behavior and no well-defined plateaus, while in the presence of H$_{2}$O molecules they exhibit a jump to contact and abrupt transitions between fractional and integer plateaus.
