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Electrical Conductivity in Quasicrystals and their Crystal Approximants

准晶体及其晶体近似物的电导率

基本信息

批准号：
04452036
负责人：
TAKEUCHI Shin
金额：
$ 4.29万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04452036/
关键词：
Quasicrystal Crystal approximant Electrical conductivity Electron localization Hopping conduction

项目摘要

1. Main results obtained for high quality samples are as follows :(1) In A1-Pd-Mn icosahedral phase, electrical resistivity increases almost linearly with deceasing temperature and shows a maximum at few tens of Kelvin and then decreases in low Mn-concentration alloys. The specific resistivity at helium temperature is generally quite high and varies from 10^3 to 10^4 mu OMEGA cm depending on the alloy composition. The temperature dependence of the resistivity, as well as the magnetoresistance effect, can be interpreted by the weak-localization theory that takes into account the spin-orbit interaction.(2) Also in Al-Pd-Re icosahedral phase, the resistivity is extremely high and varies sensitively with the composition. In some Al_<70>Pd_<20>Re_<10> alloys, the resistivity value reaches as high as 1O MEGA cm at helium temperature, which is the highest value ever reported for quasicrystals. Temperature and magnetic field dependences of the resistivity are interpreted by the weak-localization theory except the samples with the highest resistivity which show hoping-like conduction.(3) In Al-Cu-Ru and Al-Cu-Fe icosahedral phases, the electrical conductivity varies as T^<1/2> below a few tens of Kelvin due to the electron-electron interaction effect and as T linear above the temperature due to the weak-localization effect. Hall coefficient measurements have suggested the temperature variation of the carrier density.2. From the experimental results so far obtained, we get the following picture : in both high-quality quasicrystals and their high-order crystal approximants, a deep pseudo-gap is always forms at the Fermi-level due to the Fermi-surface quasi-Brillouin zone boundary interaction, and the electrons near the Fermi-level have a stronger tendency to localize as the pseudo-gap deepens ; these circumstances produce characteristic behavior of electrical resistivity in quasicrystals.

1.（1）在A1-Pd-Mn二十面体相合金中，电阻率随温度的降低几乎呈线性增加，在几十K处出现最大值，而在低Mn含量时，电阻率又逐渐减小。氦温度下的电阻率通常很高，根据合金成分的不同，从10^3到10^4 μ Ω cm不等。的电阻率的温度依赖性，以及磁阻效应，可以解释的弱局域化理论，考虑到自旋轨道相互作用。(2)同样在Al-Pd-Re二十面体相中，电阻率非常高，并且随组成敏感地变化。在某些Al_Pd_Re_合金中，在氦温下的电阻率值高达10 M Ω cm，这是迄今所报道的准晶的最高值。<70><20><10>电阻率的温度和磁场依赖性的解释弱局域化理论，除了具有最高电阻率的样品，表现出Hoping-like导电。(3)在Al-Cu-Ru和Al-Cu-Fe二十面体相中，由于电子-电子相互作用效应，电导率在几十K以下随T ^<1/2>变化，而由于弱局域化效应，电导率在温度以上随T线性变化。霍尔系数的测量表明载流子密度随温度的变化.从目前的实验结果可以看出：无论是高质量准晶还是它们的高阶近似晶体，由于费米面准布里渊区边界相互作用，在费米能级上总是形成一个深的赝能隙，随着赝能隙的加深，费米能级附近的电子有更强的局域化倾向;这些情况在准晶中产生电阻率的特征行为。