Electronic States in Two-dimensional Quasicrystals

二维准晶体中的电子态

基本信息

批准号：
06452054
负责人：
TAKEUCHI Shin
金额：
$ 3.97万
依托单位：
Institute for Solid State Physics, Univ.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：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

1.High-order approximant crystals of decagonal phase with lattice constants of a few nm have been produced for Al-Pd-Fe and Al-Co systems. The resistivity along the c-axis of these approximant crystals shows a metallic behavior, while the resistivity in the pseudo-quasicrystalline plane is an order higher than that along the c-axis and exhibits very small temperature dependence. These results are essentially the same as those of decagonal quasicrystals previously obtained, and are consistent with the theoretical results obtained by Fujiwara et al.in whihc the high resistivity in the (pseudo-) quasicrystalline plane is attributed to a very large effective mass of electrons as a result of localization of wavefunctions in atomic cluster columns along the c-axis.2.Scanning tunneling microscopy (STM) observation has been made for single crystals of an Al-Co-Ni decagonal quasicrystals produced by slow solidification from the melt. Observation has been made for tenfold-symmetric plane of the decagonal quasicrystal after Ar-ion sputtering and anealing. STM image has been obtained with a bias voltage of -0.1V and a set-current of 1nA.STM images often showed an irregular mottled pattern with a wavelength of a few nm. The pattern is quite similar to that of spatial distribution of the amplitude of the wavefunction of elctrons near the Fermi-level theoreticaly calculated by Fujiwara et al.and hence the observed pattern is considered to reflect the spatial localization of electrons.Thus, the special electronic states in two-dimensional quasicrystals have been experimentally clarified to a large extent.

1.为Al-PD-FE和Al-CO系统生产了甲状腺晶格常数的脱甲相的高阶近似晶体。这些近似晶体的C轴电阻率显示出金属行为，而伪Quasicrystalline平面的电阻率是沿C轴高的阶，并且表现出非常小的温度依赖性。这些结果基本上与先前获得的脱挥发性晶体的结果基本相同，并且与Fujiwara等人获得的理论结果一致。在（伪）准晶体平面中高电阻率归因于非常大的电子质量，这是非常有效的电子质量，这是由于波浪形的局部性。显微镜（STM）的观察是针对由熔体缓慢固化产生的al-CO-NI脱甲晶体的单晶。已经对Ar-ion溅射和启动后的十倍对称平面进行了观察。已经以-0.1V的偏置电压获得了STM图像，1NA.STM图像的设定电流通常显示出不规则的斑驳图案，其波长为几个nm。该模式与Fujiwara等人计算的Fermi级别理论附近的Elctron振幅的空间分布非常相似，因此，观察到的模式被认为反映了电子的空间定位。