Lewis George R, Wolf Daniel, Lubk Axel, Ringe Emilie, Midgley Paul A
Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0FS, UK; Department of Earth Sciences, University of Cambridge, Cambridge, CB2 3EQ, UK.
Institute for Solid State Research, IFW Dresden, Helmholtzstrasse 20, 01069, Dresden, Germany.
Ultramicroscopy. 2023 Nov;253:113804. doi: 10.1016/j.ultramic.2023.113804. Epub 2023 Jul 1.
Magnetic vector electron tomography (VET) is a promising technique that enables better understanding of micro- and nano-magnetic phenomena through the reconstruction of 3D magnetic fields at high spatial resolution. Here we introduce WRAP (Wavelet Regularised A Program), a reconstruction algorithm for magnetic VET that directly reconstructs the magnetic vector potential A using a compressed sensing framework which regularises for sparsity in the wavelet domain. We demonstrate that using WRAP leads to a significant increase in the fidelity of the 3D reconstruction and is especially robust when dealing with very limited data; using datasets simulated with realistic noise, we compare WRAP to a conventional reconstruction algorithm and find an improvement of ca. 60% when averaged over several performance metrics. Moreover, we further validate WRAP's performance on experimental electron holography data, revealing the detailed magnetism of vortex states in a CuCo nanowire. We believe WRAP represents a major step forward in the development of magnetic VET as a tool for probing magnetism at the nanoscale.
磁矢量电子断层扫描（VET）是一项很有前景的技术，它能够通过高空间分辨率重建三维磁场，从而更好地理解微观和纳米磁性现象。在此，我们介绍WRAP（小波正则化算法程序），这是一种用于磁VET的重建算法，它使用压缩感知框架直接重建磁矢势A，该框架在小波域中对稀疏性进行正则化。我们证明，使用WRAP可显著提高三维重建的保真度，并且在处理非常有限的数据时特别稳健；使用具有实际噪声的模拟数据集，我们将WRAP与传统重建算法进行比较，发现在几个性能指标上平均提高了约60%。此外，我们进一步在实验电子全息数据上验证了WRAP的性能，揭示了CuCo纳米线中涡旋态的详细磁性。我们相信，WRAP代表了磁VET作为一种探测纳米尺度磁性的工具发展中的一个重大进步。
