Vibrational dynamics of Fe in amorphous Fe鈥揝c and Fe鈥揂l alloy thin films
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- 作者：B. Sahoo ; W. Keune ; E. Schuster ; W. Sturhahn ; J. Zhao ; T. S. Toellner and E. E. Alp
- 关键词：amorphous alloys ; Fe– ; Sc ; Fe– ; Al ; thin films ; conversion electron M枚ssbauer spectroscopy (CEMS) ; nuclear resonant inelastic X ; ray scattering ; atomic vibrational density of states ; boson peak
- 刊名：Hyperfine Interactions
- 出版时间：June, 2006
- 出版年：2006
- 期刊代码：18_03043843
- 类别：cp
- 卷：170
- 期：1-3
- 页码：33-46
- 数据来源：sp
摘要
The atomic vibrational dynamics of 57Fe in 800-脜 thick amorphous (a-) 57Fe0.25Sc0.75, a-57Fe0.67Sc0.33 and a-57Fe0.14Al0.86 alloy thin films has been investigated at room temperature by nuclear resonant inelastic X-ray scattering (NRIXS) of synchrotron radiation. The amorphous phase has been successfully stabilized by codeposition of Fe and Sc or Al in ultrahigh vacuum onto substrates held at –140 掳C during deposition. The amorphous structure of the samples was confirmed by X-ray diffraction and conversion electron M枚ssbauer spectroscopy. The 57Fe-projected partial vibrational density of states, g(E), has been obtained from the measured NRIXS vibrational excitation probability, together with thermodynamic quantities such as the probability of recoilless absorption (f-factor), the average kinetic energy per Fe atom, the average force constant, and the vibrational entropy per Fe atom. A plot of the reduced density of states, g(E)/E2, versus excitation energy E proves the existence of non-Debye-like vibrational modes (boson peak) with a peak energy, E bp , in the range of 3–7 meV. Both, the boson peak height H bp and E bp were found to depend on the composition. Above the boson peak, g(E)/E2 exhibits an exponential decrease. Our results demonstrates that the features of the boson peak depend on the amount and type of element M (M = Al, Si, Mg, Sc).