Probing bulk states of correlated electron systems by high-resolution resonance photoemission
Probing bulk states of correlated electron systems by high-resolution resonance photoemission
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DOI：
10.1038/35000140
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发表时间：
2000-01
期刊：
影响因子：
64.8
通讯作者：
A. Sekiyama;T. Iwasaki;K. Matsuda;Y. Saitoh;Y. Ōnuki;S. Suga
中科院分区：
文献类型：
--
作者：
A. Sekiyama;T. Iwasaki;K. Matsuda;Y. Saitoh;Y. Ōnuki;S. Suga
电子相关性在确定各种化合物的不寻常物理性质方面起着重要作用。这些性质包括高温超导性、重费米子行为和金属到绝缘体的转变。高分辨率光电子能谱（PES）提供了一种直接探测这些材料中的电子态（特别是费米能级附近的电子态）的方法，但与传统使用的低激发能量（120 eV）相关的短光电子平均自由程（150 eV）使其成为表面敏感技术。现在，高分辨率PES是可能的，在更高的能量，平均自由程长达15 μ m（参考），它应该成为可行的探测这些材料中的体电子态。在这里，我们证明了这种技术的力量，通过将其应用到铈化合物CeRu2Si2和CeRu2。以前的PES研究这些化合物揭示了非常相似的光谱为Ce 4f电子状态，但预计这些国家应该是不同的，由于其不同程度的杂交与其他价带。我们确定的这些化合物的体Ce 4f电子态解决了这些差异。
Electron correlations are known to play an important role in determining the unusual physical properties of a variety of compounds. Such properties include high-temperature superconductivity, heavy fermion behaviour,and metal-to-insulator transitions,. High-resolution photoelectron spectroscopy (PES) provides a means of directly probing the electronic states (particularly those near the Fermi level) in these materials, but the short photoelectron mean free paths (⩽5 Å) associated with the low excitation energies conventionally used (⩽120 eV) make this a surface-sensitive technique. Now that high-resolution PES is possible at much higher energies, with mean free paths as long as 15 Å (ref. ), it should become feasible to probe the bulk electronic states in these materials. Here we demonstrate the power of this technique by applying it to the cerium compounds CeRu2Si2and CeRu2. Previous PES studies of these compounds revealed very similar spectra for the Ce 4felectronic states,,,,,, yet it is expected that such states should be different owing to their differing degrees of hybridization with other valence bands. Our determination of the bulk Ce 4felectronic states of these compounds resolves these differences.