Quasicrystalline valence bands in decagonal AlNiCo
Quasicrystalline valence bands in decagonal AlNiCo
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DOI：
10.1038/35020519
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发表时间：
2000-08
期刊：
影响因子：
64.8
通讯作者：
E. Rotenberg;W. Theis;K. Horn;P. Gille
中科院分区：
文献类型：
--
作者：
E. Rotenberg;W. Theis;K. Horn;P. Gille
准晶是具有完美长程结构有序性的金属合金，尽管它们的旋转对称性与长程周期性不相容。这类材料的奇异结构特性伴随着金属合金意想不到的物理特性。利用X射线和中子衍射在解决准晶的几何结构方面取得了相当大的进展，准晶胞模型等概念提供了理论见解。但是，价电子态的基本性质--无论是在周期性晶体中扩展的，还是在非晶材料中局域化的--仍然在很大程度上没有得到解决。在这里，我们调查的电子能带结构的准晶通过角分辨光电子能谱实验十次对称Al 71.8Ni 14.8Co 13.4。我们发现，这些pandd态表现出类带行为与准周期晶格的对称性，费米能级被分散带穿过。根据表面衍射图样，在动量空间中分布的类自由电子带的观察表明，电子态不受局域化的支配。
Quasicrystals are metallic alloys that possess perfect long-range structural order, in spite of the fact that their rotational symmetries are incompatible with long-range periodicity. The exotic structural properties of this class of materials are accompanied by physical properties that are unexpected for metallic alloys. Considerable progress in resolving the geometric structures of quasicrystals has been made using X-ray and neutron diffraction, and concepts such as the quasi-unit-cell model have provided theoretical insights. But the basic properties of the valence electronic states—whether they are extended as in periodic crystals or localized as in amorphous materials—are still largely unresolved. Here we investigate the electronic bandstructure of quasicrystals through angle-resolved photoemission experiments on decagonal Al71.8Ni14.8Co13.4. We find that thes-panddstates exhibit band-like behaviour with the symmetry of the quasiperiodic lattice, and that the Fermi level is crossed by dispersingd-bands. The observation of free-electron-like bands, distributed in momentum space according to the surface diffraction pattern, suggests that the electronic states are not dominated by localization.