Surface electronic structure of fcc Co films: a combined spin-resolved one- and two-photon-photoemission study
Surface electronic structure of fcc Co films: a combined spin-resolved one- and two-photon-photoemission study
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fcc Co 薄膜的表面电子结构：自旋分辨单光子和双光子光电发射联合研究
DOI：
10.1088/0022-3727/41/16/164003
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
M. Donath
中科院分区：
文献类型：
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作者：
A. Schmidt;M. Pickel;T. Allmers;M. Budke;J. Braun;M. Weinelt;M. Donath
用自旋分辨单光子和双光子光电子能谱研究了Cu（0 0 1）衬底上面心立方钴薄膜的表面电子结构。少数能带结构的Δ1对称带隙中的少数表面态在费米能级以下约0.45 eV处被识别。在p偏振光激发的双光子光电发射实验中，该态引起少数像势表面态布居的类共振增强。此外，它出现在正常的光电发射（PE）的表面敏感的光谱特征，它的存在证实了PE的一步模型内的计算。表面态的大多数对应物理论上预期在约1.95 eV的结合能处。由于在此能量范围内的寿命加宽和体跃迁，多数态在光谱中不作为显著特征出现。体衍生的状态接近费米能级表现出更高的结合能随着膜厚度的增加，而少数表面态不改变其能量作为一个功能的Co覆盖。这些结果提供了一个解释的时间分辨的测量超快磁化动力学，这依赖于一个详细的知识的表面电子结构的SiO2薄膜的基础。
The surface electronic structure of face-centred-cubic cobalt films on Cu(0 0 1) was studied by spin-resolved one- and two-photon photoemission. A minority surface state in a Δ1-symmetry gap of the minority band-structure was identified at about 0.45 eV below the Fermi energy. This state causes a resonance-like enhancement in the population of the minority image-potential surface state in the two-photon-photoemission experiment excited by p-polarized light. Additionally, it appears as a surface-sensitive spectral feature in normal photoemission (PE) and its existence is confirmed by calculations within the one-step model of PE. The majority counterpart of the surface state is theoretically expected at a binding energy of about 1.95 eV. Due to lifetime broadening and bulk transitions in this energy range, the majority state does not appear as a pronounced feature in the spectra. Bulk-derived states close to the Fermi level exhibit shifts to higher binding energy with increasing film thickness, while the minority surface state does not change its energy as a function of Co coverage. These results provide a basis for the interpretation of time-resolved measurements concerning ultrafast magnetization dynamics, which rely on a detailed knowledge of the surface electronic structure of ultrathin films.
a.Schmid：“Cu(100) 上 Co 薄膜外延生长的原位观察”超显微术。
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