Properties of novel one-dimensional metals on solid surfaces

固体表面上新型一维金属的特性

基本信息

批准号：
13440094
负责人：
ARUGA Tetsuya
金额：
$ 9.09万
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：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

There.is a growing interest. in phase transitions in nanometer-scale materials, which include charge-density-wave (CDW) phase transitions, which are driven by the electron-phonon interaction in metallic materials with low-dimensional electron systems and are associated with changes in transport properties.As solid surfaces and interfaces provide quasi-two-dimensional electron systems, efforts have long been paid to find CDW transitions, which fruited recently in the discovery of intriguing surface phase transitions. We have carried out a detailed study, by means of angle-resolved photoemission, surface X-ray diffraction, scanning tunneling microscopy, low-energy electron diffraction and first-principles all-electron DFT calculation, on the phase transition observed at 350-400 K on the Cu(001) surface covered with 0.65-ML In. The surface exhibits a c(4x4) structure in the low-temperature (LT) phase and undergoes a reversible transition to high-temperature (HT) p(2x2) phase. The most important finding was deduced from the temperature dependence of the energy gap associated with the CDW formation and the diffraction profile from the CD.W phass. While the former results shows a clear evidence for the BCS-like behavior of the CDW gap with Tc(elec) = 400 K, supporting the weak-coupling'CDW theory, the latter result indicates unambiguously that the orderdisorder phase transition classified into 2D Ising universality class takes place. at Tc(lattice) = 345 K. These seemingly contradicting results point to a scenario that the two qualitatively different phase transitions take place concertedly at the same temperature range, which we ascribe to the enhanced fluctuation effect and the unique dimensionality inherent to surface systems.We also studied on the diffusion and coalescence of the 2D surface alloy islands on Al/Pd(001), the electronic driving mechanism of the p4g lattice distortion and its lifting by hydrogen adsorption on the Ti/Pd(001) surface alloy.

那里越来越兴趣。 in phase transitions in nanometer-scale materials, which include charge-density-wave (CDW) phase transitions, which are driven by the electron-phonon interaction in metallic materials with low-dimensional electron systems and are associated with changes in transport properties.As solid surfaces and interfaces provide quasi-two-dimensional electron systems, efforts have long been paid to find CDW transitions, which fruited recently in the discovery of intriguing表面相变。我们通过角度分辨光发射，表面X射线衍射，扫描隧道显微镜，低能量电子衍射和第一原理全电子DFT计算进行了一项详细的研究，该研究在350-400 K上观察到的相变。表面在低温（LT）相中表现出A C（4x4）结构，并经历了可逆的过渡到高温（HT）P（2x2）相。最重要的发现是从与CDW形成相关的能量差距和CD.W Phass的衍射曲线相关的温度依赖性中得出的。尽管前者的结果显示了CDW差距（ELEC）= 400 K的BCS样行为有明确的证据，支持弱耦合'CDW理论，后者的结果明确表明，分类为2D Ising Gressital类别的OrderDisorder阶段过渡分类为2D。在TC（晶格）= 345K处。这些看似矛盾的结果表明，两个不同的相过渡在相同的温度范围内进行了两种不同的相位过渡，我们将其归因于增强的波动效应以及表面系统固有的独特尺寸性，我们还对2D表面合同岛的扩散和cocerion of Aly/pd of 41的独特尺寸（我们还研究）。晶格失真及其在Ti/Pd（001）表面合金上通过氢吸附提升。