Valence band structure of the icosahedral Ag-In-Yb quasicrystal
Valence band structure of the icosahedral Ag-In-Yb quasicrystal
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DOI：
10.1103/physrevb.81.104205
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发表时间：
2010-03-01
影响因子：
3.7
通讯作者：
Ishii, Y.
中科院分区：
文献类型：
--
作者：
Sharma, H. R.;Simutis, G.;Ishii, Y.
用紫外光电子能谱（UPS）研究了与i-Cd-Yb二元系同构的二十面体（i）Ag-In-Yb准晶的价带结构。实验结果进行了比较，与电子结构计算的立方近似相同的相位。五重、三重和二重i-Ag-In-Yb表面的UPS光谱表明，在费米能级附近的价带主要由Yb 4f-衍生态占据，与计算结果一致.光谱还表现出表面芯能级移动的峰，这是由表面层中的电子结构的变化引起的。计算产生的赝能隙的状态密度由于与银5 p和在5 p带的Yb 5d带的杂交。实验和计算的能带特征都与Cd-Yb非常相似。通过溅射和氧化表面处理后的能带结构的修改也进行了研究。此外，从UPS谱的宽度测量的i-Ag-In-Yb的功函数被发现几乎不受表面取向的影响，但增加后溅射或氧化。
The valence band structure of the icosahedral (i) Ag-In-Yb quasicrystal, which is isostructural to the binary i-Cd-Yb system, is investigated by ultraviolet photoemission spectroscopy (UPS). Experimental results are compared with electronic-structure calculations of a cubic approximant of the same phase. UPS spectra from the fivefold, threefold, and twofold i-Ag-In-Yb surfaces reveal that the valence band near to the Fermi level is dominated by Yb 4f-derived states, in agreement with calculations. The spectra also exhibit peaks which are surface core level shifted, caused by changes in the electronic structure in surface layers. Calculations yield a pseudogap in the density of states due to a hybridization of the Yb 5d band with the Ag 5p and In 5p bands. Both experimental and calculated band features are very similar to those of Cd-Yb. The modification of the band structure after surface treatment by sputtering and by oxidation is also studied. Additionally, the work function of i-Ag-In-Yb measured from the width of UPS spectrum is found to be almost unaffected by surface orientation, but increases after sputtering or oxidation.