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Conductance in Nanocontacts of Soft Metals and Liquid Metals

软金属和液态金属纳米接触的电导

基本信息

批准号：
11440092
负责人：
SAKAI Akira
金额：
$ 8.96万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

It is well known that the conductance quantization in quantum point contacts of metals can be best observed in soft metals such as Au. However, no systematic studies have been performed so far on how mechanical strength of metals influences the conductance quantization in their contacts. This study was conducted through 1999-2000 fiscal years to clarify the interrelation between hardness of metals and the appearance of conductance quantization in their atom-sized contacts. Main results obtained in this work are listed below.1. We investigated the conductance of five transition metals of different hardness, Pd, Pt, Rh, Ru, and Ir, and found that none of them exhibit the conductance quantization as clearly as that of Au. However, the conductance characteristics depends on metals, and a weak correlation can be found between the degree of conductance quantization and the mechanical strength of metals.2. Although liquid Hg represents the softest metals, it also exhibits hardly any evidences … More of the conductance quantization. We found that the conductance characteristics of Hg depend on the speed of contact breaking. In fast-breaking relay contacts, Hg shows no conductance plateaus in transient conductance traces. With the use of a slow-breaking mechanical contact, we can observe, not often but occasionally, well-defined quantized conductance plateaus.3. Alloying is a typical method of strengthening metals. We, therefore, carried out experiments on AuPd alloys to clarify the influence of alloying on the conductance quantization. In AuPd, it is found that the conductance characteristics transform gradually from that of pure Au to that of pure Pd with increasing the Pd concentration. Quantized conductance peaks in the histogram of Au are reduced by alloying with Pd, and gradually replaced by a broad structure characteristic of the Pd histogram. An important finding is that the first conductance peak shows no peak shift upon Pd alloying. This observation suggests that the electron scattering by solute atoms is much stronger than to generate the peak shift. Less

众所周知，金属量子点接触中的电导量子化在Au等软金属中最容易观察到。然而，到目前为止，还没有关于金属的机械强度如何影响其接触中的电导量子化的系统研究。这项研究是在1999-2000财政年度进行的，目的是阐明金属硬度与其原子大小的接触中出现的电导量子化之间的相互关系。本工作取得的主要成果如下1.我们研究了五种不同硬度的过渡金属Pd、Pt、Rh、Ru和Ir的电导，发现它们都没有Au那么明显的电导量子化。然而，电导特性依赖于金属，并且电导量子化程度与金属的机械强度之间存在弱相关性。尽管液态汞代表最软的金属，但它也几乎没有任何证据表明…更多的是电导的量子化。我们发现，汞的电导特性依赖于触点开断的速度。在快断继电器触点中，汞在暂态电导轨迹中没有表现出电导平台。通过使用慢速断裂的机械接触，我们可以观察到明确的量化电导平台，这不是经常的，而是偶尔的。合金化是一种典型的金属强化方法。因此，我们对AuPd合金进行了实验，以阐明合金化对电导量子化的影响。在AuPd中发现，随着Pd浓度的增加，电导特性由纯Au的电导特性逐渐转变为纯Pd的电导特性。Pd的合金化降低了Au直方图中量子化的导电峰，并逐渐被广泛的Pd直方图的结构特征所取代。一个重要的发现是，Pd合金化的第一个电导峰没有峰位移。这表明，电子被溶质原子的散射比产生峰位移要强得多。较少