Probing the timescale of the exchange interaction in a ferromagnetic alloy
Probing the timescale of the exchange interaction in a ferromagnetic alloy
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DOI：
10.1073/pnas.1201371109
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发表时间：
2012-03-27
影响因子：
11.1
通讯作者：
Kapteyn, Henry C.
中科院分区：
文献类型：
--
作者：
Mathias, Stefan;La-O-Vorakiat, Chan;Kapteyn, Henry C.
所有铁磁行为的基础物理是导致宏观磁化的单个原子磁矩之间的合作相互作用。在这项工作中，我们使用高次谐波产生的极紫外脉冲作为铁磁Fe-Ni合金（坡莫合金）中超快、光驱动、退磁的元素特异性探针。我们表明，时间短于交换耦合的特征时间尺度，铁的磁化淬火更强烈的比镍。然后，随着Fe矩开始随机化，强铁磁交换相互作用引起Ni中的进一步退磁，具有由交换相互作用的强度确定的特征延迟。我们可以通过用Cu稀释坡莫合金来降低交换能来进一步增强这种延迟。该测量探讨了磁性材料中Fe和Ni之间的基本量子力学交换耦合如何影响与下一代数据存储技术相关的铁磁材料中的磁开关动力学。
The underlying physics of all ferromagnetic behavior is the cooperative interaction between individual atomic magnetic moments that results in a macroscopic magnetization. In this work, we use extreme ultraviolet pulses from high-harmonic generation as an element-specific probe of ultrafast, optically driven, demagnetization in a ferromagnetic Fe-Ni alloy (permalloy). We show that for times shorter than the characteristic timescale for exchange coupling, the magnetization of Fe quenches more strongly than that of Ni. Then as the Fe moments start to randomize, the strong ferromagnetic exchange interaction induces further demagnetization in Ni, with a characteristic delay determined by the strength of the exchange interaction. We can further enhance this delay by lowering the exchange energy by diluting the permalloy with Cu. This measurement probes how the fundamental quantum mechanical exchange coupling between Fe and Ni in magnetic materials influences magnetic switching dynamics in ferromagnetic materials relevant to next-generation data storage technologies.