Description
In recent years, there has been a growing interest from the magnetism community in expanding to three-dimensional magnetic systems [1,2] – from exploring new geometries to revealing complex magnetic textures arising in extended samples [3-5]. A key aspect of this exploration is the ability to visualize the magnetization vector field at the nanoscale throughout the entire sample, made possible by the development of 3D magnetic imaging [6]. This technique can achieve nanometric spatial resolution in micrometer-thick samples by leveraging the penetration depth and coherence of synchrotron X-rays [7,8,9]. Indeed, the coherence of the X-ray beam provides magnetic contrast not only in the absorption of the transmitted wave, but also in the phase. This phase contrast enables the investigation of micron-sizes magnets, even with soft X-rays, while minimizing the sample damage [7]. Here, we present a new tomographic technique [9] based on Fourier transform holography, a lensless imaging technique that uses a known reference in the sample to retrieve the object of interest from its diffraction pattern in one single step of calculation. We obtain a 3D vectorial image of an 850nm-thick extended Fe/Gd multilayer in a 5μm-diameter field of view with a resolution of 80 nm. Visualizing the magnetization vector field with nanometer spatial resolution in extended samples opens the door to studying magnetic textures in higher dimensions, offering insights into fundamental physical phenomena as well as promising new applications in information storage and processing.
[1] Streubel et al., J. Phys. D 49, 363001 (2016)
[2] Fernández-Pacheco et al., Nat. Commun. 8, 15756 (2017)
[3] Hierro-Rodriguez et al., Nat. Commun. 11, 6382 (2020)
[4] Donnelly et al., Nature Physics 17, 316–321 (2021)
[5] Kent et al., Nat. Commun. 12, 1562 (2021)
[6] Donnelly et al., Nature 547, 328 (2017)
[7] Scherz et al. Phys. Rev. B 76, 214410 (2007).
[8] Di Pietro Martínez et al., PRB 107, 094425 (2023)
[9] Neethirajan et al. PRX 14, 3 (2024)
