Zhang Wentao, Maldonado Pablo, Jin Zuanming, Seifert Tom S, Arabski Jacek, Schmerber Guy, Beaurepaire Eric, Bonn Mischa, Kampfrath Tobias, Oppeneer Peter M, Turchinovich Dmitry
Fakultät für Physik, Universität Bielefeld, Universitätsstr. 25, 33615, Bielefeld, Germany.
Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.
Nat Commun. 2020 Aug 25;11(1):4247. doi: 10.1038/s41467-020-17935-6.
A material's magnetic state and its dynamics are of great fundamental research interest and are also at the core of a wide plethora of modern technologies. However, reliable access to magnetization dynamics in materials and devices on the technologically relevant ultrafast timescale, and under realistic device-operation conditions, remains a challenge. Here, we demonstrate a method of ultrafast terahertz (THz) magnetometry, which gives direct access to the (sub-)picosecond magnetization dynamics even in encapsulated materials or devices in a contact-free fashion, in a fully calibrated manner, and under ambient conditions. As a showcase for this powerful method, we measure the ultrafast magnetization dynamics in a laser-excited encapsulated iron film. Our measurements reveal and disentangle distinct contributions originating from (i) incoherent hot-magnon-driven magnetization quenching and (ii) coherent acoustically-driven modulation of the exchange interaction in iron, paving the way to technologies utilizing ultrafast heat-free control of magnetism. High sensitivity and relative ease of experimental arrangement highlight the promise of ultrafast THz magnetometry for both fundamental studies and the technological applications of magnetism.
材料的磁状态及其动力学具有重大的基础研究价值，也是众多现代技术的核心。然而，在技术相关的超快时间尺度上，以及在实际器件运行条件下，可靠地获取材料和器件中的磁化动力学仍然是一个挑战。在此，我们展示了一种超快太赫兹（THz）磁测量方法，该方法能够以非接触方式、完全校准的方式以及在环境条件下，直接获取甚至是封装材料或器件中的（亚）皮秒磁化动力学。作为这种强大方法的一个实例，我们测量了激光激发的封装铁膜中的超快磁化动力学。我们的测量揭示并区分了源自以下两方面的不同贡献：（i）非相干热磁子驱动的磁化猝灭，以及（ii）铁中交换相互作用的相干声子驱动调制，为利用超快无热磁控制的技术铺平了道路。高灵敏度和相对简便的实验设置凸显了超快太赫兹磁测量在磁学基础研究和技术应用方面的前景。
