Valence characterisation of the subsurface region in
Valence characterisation of the subsurface region in
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DOI：
10.1080/14786435.2016.1192724
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发表时间：
2016-05
影响因子：
1.6
通讯作者：
P. Lutz;M. Thees;T. Peixoto;B. Kang;B. Cho;C. Min;F. Reinert
中科院分区：
文献类型：
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作者：
P. Lutz;M. Thees;T. Peixoto;B. Kang;B. Cho;C. Min;F. Reinert
六硼化钐（）在安德森模型中处于混合价态，被预测具有拓扑保护的表面态。对稀土化合物的深入研究提出了一个长期存在的问题，即稀土化合物的表面电子性质与体电子性质之间的差异。在这里，我们研究并最终澄清了这种差异在特定情况下的光电发射核心能级光谱。我们重点研究了Sm和B态随时间、温度、探测深度和切割（1 0 0）表面终止的变化。我们的光谱显示，Sm价的不寻常的随时间变化发生在一段时间内，这与残余气体的吸附无关。此外，我们观察到在同一时间尺度上，B态和Sm态的表面特征减少，并伴有地下区域的形成。因此，它表明表面和亚表面区域之间的电荷重新分配相对缓慢。我们的发现表明f态在表面弛豫中起着重要的作用。
Samarium hexaboride (), which lies in the mixed valence regime in the Anderson model, has been predicted to possess topologically protected surface states. The intensive investigations on have brought up the long-standing questions about the discrepancy between the surface and bulk electronic properties in rare earth compounds in general. Here, we investigate and eventually clarify this discrepancy in the particular case of by the photoemission core-level spectra. We focus on the change in both Sm and B states depending on time, temperature, probing depth and surface termination on the cleaved (1 0 0) surface. Our spectra show that the unusual time-dependent change in the Sm valence occurs within a period of hours, which is not related to the adsorption of residual gases. Moreover, we observe a reduction of the surface feature in the B and Sm states on the same timescale accompanied by the formation of a subsurface region. Thus, it indicates the relatively slow charge redistribution between the surface and subsurface regions. Our findings demonstrate that the f states is strongly involved in the surface relaxation.