Magnetisation switching of FePt nanoparticle recording medium by femtosecond laser pulses.
Magnetisation switching of FePt nanoparticle recording medium by femtosecond laser pulses.
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DOI：
10.1038/s41598-017-04167-w
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发表时间：
2017-06-23
影响因子：
4.6
通讯作者：
Münzenberg M
中科院分区：
文献类型：
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作者：
John R;Berritta M;Hinzke D;Müller C;Santos T;Ulrichs H;Nieves P;Walowski J;Mondal R;Chubykalo-Fesenko O;McCord J;Oppeneer PM;Nowak U;Münzenberg M
用超短激光脉冲操纵磁化对于信息存储设备应用来说是有希望的。磁化响应的动力学取决于初始激光激发期间从光子到自旋的能量转移。对于磁存储特别感兴趣的材料是 FePt 纳米粒子，最近证明了其磁化强度随光学角动量的切换。其机制仍不清楚。在这里，我们从实验和理论上研究了 FePt 纳米粒子的全光开关。我们证明磁化强度翻转是一个随机过程。我们开发了一个完整的多尺度模型，使我们能够优化实验中切换高各向异性 FePt 纳米颗粒磁化强度所需的激光发射数量。我们得出的结论是，只有由反法拉第效应光学诱导的角动量才能提供单个飞秒激光脉冲的切换。
Manipulation of magnetisation with ultrashort laser pulses is promising for information storage device applications. The dynamics of the magnetisation response depends on the energy transfer from the photons to the spins during the initial laser excitation. A material of special interest for magnetic storage are FePt nanoparticles, for which switching of the magnetisation with optical angular momentum was demonstrated recently. The mechanism remained unclear. Here we investigate experimentally and theoretically the all-optical switching of FePt nanoparticles. We show that the magnetisation switching is a stochastic process. We develop a complete multiscale model which allows us to optimize the number of laser shots needed to switch the magnetisation of high anisotropy FePt nanoparticles in our experiments. We conclude that only angular momentum induced optically by the inverse Faraday effect will provide switching with one single femtosecond laser pulse.