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Study on spin structures and electron-lattice interaction of nanomaterials using nuclear resonant scattering.

利用核共振散射研究纳米材料的自旋结构和电子晶格相互作用。

基本信息

批准号：
15540308
负责人：
SETO Makoto
金额：
$ 2.11万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

Nanostructured materials like quantum wires have attracted much interest for their novel properties and the possibilities for new devices. It is well known that nanostructured materials show different electric and thermodynamical properties as compared to ordinary macroscopic materials. For the further understanding and new applications, microscopic studies on nanosized materials are indispensable.We have measured the time and energy spectra of nuclear resonant scattering of synchrotron radiation from magnetic Fe nanowires to investigate the electronic states and lattice dynamics of the Fe nanowires, As for the electronic states, we studied the correlation between the spin structure and the shape of the wires. From the measured time spectra of the Fe nanowires, the value of internal magnetic field is obtained to be 32.9 T. This agrees with the value of the bulk Fe (33 T), and this result indicates the electronic state of Fe atoms in our nanowire sample is almost the same as that of Fe atoms in a bulk sample. Furthermore, it was confirmed that the direction of the magnetic field is anisotropic and coincides with the direction of the nanowires. Our results show that this method is useful for the study of electronic states of nanomaterilas. As for the vibrational states, we studied the difference between the bulk state and the nanowires. Because it is possible to obtain the information on the specific elements by using nuclear resonant scattering, we can obtain the intrinsic lattice dynamics of nanoweires without the vibration of the substrate material. The observed phonon spectra show the dependence on the size of the samples, and we concluded it is due to the anharmonic effect.

像量子线这样的纳米结构材料因其新颖的特性和新设备的可能性而引起了人们的极大兴趣。众所周知，纳米结构材料与普通宏观材料相比，具有不同的电学和热力学性质。对于纳米材料的进一步认识和新的应用，微观研究是必不可少的。我们测量了磁性铁纳米线同步辐射核共振散射的时间谱和能谱，研究了铁纳米线的电子态和晶格动力学，研究了自旋结构与铁纳米线形状的关系。从所测得的铁纳米线的时间谱中，得到了内部磁场的值为32.9 T，这与块体铁的值（33 T）一致，这表明我们的纳米线样品中的铁原子的电子态与块体样品中的铁原子的电子态几乎相同。进一步证实了磁场方向是各向异性的，且与纳米线的方向一致。结果表明，该方法可用于纳米材料的电子态研究。在振动态方面，我们研究了体态与纳米线的区别。由于利用核共振散射可以获得特定元素的信息，我们可以在没有衬底材料振动的情况下获得纳米线的本征晶格动力学。观察到的声子光谱与样品的大小有关，我们认为这是由于非谐波效应。