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High resoeution, high energy spectroscopy of electronic states on phase transitions

相变电子态的高分辨率、高能谱

基本信息

批准号：
08405004
负责人：
SUGA Shigemasa
金额：
$ 16.26万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1999
项目状态：
已结题

项目摘要

Changes of electronic states near the Fermi level on phase transitions are extensivelu studied by means of high resolution spectroscopy. The resonance photoemission technique was intensively employed. In the former half of the research, the spectral changes of the low carrier heavy fermion system YbィイD24ィエD2AsィイD23ィエD2 and related compounds were studied. The high reslution photoemission was successfully performed in the Kondo insulator system YbBィイD212ィエD2. In the case of the NdィイD21-xィエD2SrィイD2xィエD2MnOィイD23ィエD2, spectral changes through paramagnetic insulator-ferromagnetic metal-charge ordered insulator were observed for x=0.5. For x=0.47, paramagnetic insulator-ferromagnetic metal transition was observed and the Fermi cut off was observed down to the lowest temperature.In the latter half of the research, we constructed and commissioned the world-best performance soft X-ray beam line at SPring-8. The photoemission performed at 900eV for Yb system has shown that the surface YbィイD12+ィエD1 is almost suppressed. Thus the deconvolution which has been always required to derive the bulk YbィイD12+ィエD1 components from the spectra measured near 100eV is no more necessary to know the genuine bulk electronic states.The situation was more severe for the Ce system, where the deconvolution was useless because of the overlap of surface and bulk components. However, our bulk sensitive photoemision technique is found to provide the bulk spectrum. Thus we have found that the Ce 4f spectra can be scaled by the Kondo temperature. This unprecedented results are published in Nature and stimulating many scientists in the world.In parallel, the structure and magnetism were theoretically studied for taransition metal nitrides and YCoB systems. The lattice constants in the nonmagnetic phase, total energy, as well as magnetic moments were calculated.

本文用高分辨光谱方法研究了相变过程中费米能级附近电子态的变化。共振光电子能谱技术得到了广泛的应用。前半部分研究了低载流子重费米子系统Yb_（10）D_（24）D_（22）As_（10）D_（23）D_（22）及其相关化合物的光谱变化。在近藤绝缘体系统YbB超导体D212超导体D2中成功地进行了高分辨光电发射。在Nd：YAG D21-x YAG D2 Sr：YAG D2 x YAG D2 MnO：YAG D23：YAG D2的情况下，在x=0.5时观察到通过顺磁绝缘体-铁磁金属-电荷有序绝缘体的光谱变化。当x=0.47时，观察到了顺磁绝缘体-铁磁金属的转变，并在最低温度下观察到了费米截止。在研究的后半部分，我们在SPring-8上建造并调试了世界上性能最好的软X射线束线。在900 eV下对Yb系统进行的光电子谱测试表明，表面Yb_xD_（12）+Yb_xD_（1）几乎被抑制。因此，从100 eV附近测量的光谱中导出体Yb_xD 12 + Yb_xD 1组分所需的解卷积对于知道真正的体电子态不再是必要的。然而，我们的体敏光电子发射技术被发现提供体光谱。因此，我们发现Ce 4f谱可以用近藤温度来定标。这一前所未有的成果发表在《自然》杂志上，激励了世界上许多科学家。同时，对转移金属氮化物和YCoB系统的结构和磁性进行了理论研究。计算了该化合物的晶格常数、总能量和磁矩。