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

像量子线这样的纳米结构材料因其新颖的性质和开发新器件的可能性而引起了人们的极大兴趣。众所周知，纳米结构材料表现出与普通宏观材料不同的电学和热力学性质。为了进一步了解和应用纳米材料，对纳米材料的微观研究是必不可少的。我们测量了磁性Fe纳米线的同步辐射核共振散射的时间和能谱，研究了Fe纳米线的电子态和晶格动力学，对于电子态，我们研究了自旋结构与铁纳米线形状的关系。由测量得到的Fe纳米线的时间谱，得到其内部磁场为32.9T，这与体相Fe(33T)的值相吻合，这一结果表明我们的纳米线样品中Fe原子的电子态与体相样品中的Fe原子的电子态基本相同。此外，还证实了磁场的方向是各向异性的，并且与纳米线的方向一致。结果表明，该方法对于研究纳米材料的电子态是有用的。至于振动态，我们研究了体态和纳米线的区别。由于可以通过核共振散射获得特定元素的信息，所以我们可以在不振动衬底材料的情况下获得纳米线的本征晶格动力学。观察到的声子谱显示了样品大小的依赖关系，我们认为这是由于非谐效应造成的。

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.