Donnelly Claire, Finizio Simone, Gliga Sebastian, Holler Mirko, Hrabec Aleš, Odstrčil Michal, Mayr Sina, Scagnoli Valerio, Heyderman Laura J, Guizar-Sicairos Manuel, Raabe Jörg
Cavendish Laboratory, University of Cambridge, Cambridge, UK.
Paul Scherrer Institute, Villigen, Switzerland.
Nat Nanotechnol. 2020 May;15(5):356-360. doi: 10.1038/s41565-020-0649-x. Epub 2020 Feb 24.
Understanding and control of the dynamic response of magnetic materials with a three-dimensional magnetization distribution is important both fundamentally and for technological applications. From a fundamental point of view, the internal magnetic structure and dynamics in bulk materials still need to be mapped, including the dynamic properties of topological structures such as vortices, magnetic singularities or skyrmion lattices. From a technological point of view, the response of inductive materials to magnetic fields and spin-polarized currents is essential for magnetic sensors and data storage devices. Here, we demonstrate time-resolved magnetic laminography, a pump-probe technique, which offers access to the temporal evolution of a three-dimensional magnetic microdisc with nanoscale resolution, and with a synchrotron-limited temporal resolution of 70 ps. We image the dynamic response to a 500 MHz magnetic field of the complex three-dimensional magnetization in a two-phase bulk magnet with a lateral spatial resolution of 50 nm. This is achieved with a stroboscopic measurement consisting of eight time steps evenly spaced over 2 ns. These measurements map the spatial transition between domain wall motion and the dynamics of a uniform magnetic domain that is attributed to variations in the magnetization state across the phase boundary. Our technique, which probes three-dimensional magnetic structures with temporal resolution, enables the experimental investigation of functionalities arising from dynamic phenomena in bulk and three-dimensional patterned nanomagnets.
理解和控制具有三维磁化分布的磁性材料的动态响应，无论从基础研究还是技术应用角度来看都非常重要。从基础角度而言，大块材料内部的磁结构和动力学仍有待描绘，包括诸如涡旋、磁奇点或斯格明子晶格等拓扑结构的动态特性。从技术角度来说，感应材料对磁场和自旋极化电流的响应对于磁传感器和数据存储设备至关重要。在此，我们展示了时间分辨磁层成像技术，这是一种泵浦 - 探测技术，它能够以纳米级分辨率以及70皮秒的同步加速器极限时间分辨率获取三维磁性微盘的时间演化信息。我们对具有50纳米横向空间分辨率的两相大块磁体中复杂三维磁化对500兆赫磁场的动态响应进行成像。这是通过在2纳秒内均匀分布的八个时间步长组成的频闪测量实现的。这些测量描绘了畴壁运动与均匀磁畴动力学之间的空间转变，这种转变归因于相界处磁化状态的变化。我们的技术能够以时间分辨率探测三维磁结构，从而实现对大块和三维图案化纳米磁体中动态现象所产生功能的实验研究。
