在FePt纳米颗粒中,特定元素的超快格子动态
Diego Turenne1, Igor Vaskivskyi, Klaus Sokolowski-Tinten2
1Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden.
Structural dynamics (Melville, N.Y.)
|November 25, 2024
概括
研究人员使用超快电子衍射 (UED) 研究激光激发后FePt纳米粒子中的原子运动. 他们发现原子的膨胀比铁原子的膨胀更大,这表明应变波驱动的膨胀.
科学领域:
- 纳米规模的科学和技术.
- 材料科学是一种材料科学.
- 凝聚物质物理学 凝聚物质物理学
背景情况:
- 在纳米尺度上研究光物质相互作用对于磁记录技术至关重要.
- 磁合金中的元素特异性原子运动在很大程度上仍未被探索,尽管自旋动力学是可访问的.
- FePt纳米粒子对高密度磁记录应用具有前景.
研究的目的:
- 在超快激光激发后,探测FePt纳米粒子中元素特异性原子运动.
- 了解响应激光能量转移的格子振动和膨胀的动态.
主要方法:
- 利用超快电子衍射 (UED) 来分析网格布拉格峰的时间演变.
- 研究 FePt 纳米粒子嵌入碳矩阵.
- 用光学秒激光脉冲激发样本.
主要成果:
- 与Pt相比,Fe子网的平均平方振动幅度显著更大,与质量差异一致.
- 观察到振动幅度的增加,因为能量从激发的电子转移到格子.
- 揭示了一个反直觉的激光诱导晶格扩张,其中Pt原子在第一个皮秒内扩展超过Fe原子.
结论:
- 特定元素的原子运动,特别是晶格膨胀,可以使用UED精确测量.
- 观察到的偏好的Pt扩张表明应变波驱动的动力学,纵向声学Pt运动主导Fe运动.
- 结果提供了对纳米级热传输和磁性纳米材料的晶格动态的见解.
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