Magnetic materials underpin our high-tech lifestyles and will play key roles in the production of clean energy and next-generation computing technologies. Studying natural magnetic materials can offer insights into animal behaviour, the role of Earth’s magnetic field over time and the formation of the solar system itself. The behaviour of magnetic materials is governed by their underlying magnetisation configuration, including magnetic domains (local areas of uniform magnetisation) and defects such as domain walls.
With magnetic systems varying from the macroscopic scale down to single atoms, and occurring in everything from natural magnetite through to carefully designed topological chiral magnets, researchers require an array of techniques to study them. Exploring magnetic textures on the order of the magnetic exchange length requires spatial resolutions of tens of nanometres or lower.
However, while using a combination of high spatial resolution soft X-ray imaging and electron microscopy allows the analysis of thin samples (≲300 nm) and surfaces, investigation of thicker samples has been limited to hard X-ray dichroic imaging, limiting 3D studies to thin films for most materials, including transition metal magnets.
In work recently published in Physical Review X, an international team of researchers led by Dr Claire Donnelly of the Max Planck Institute for Chemical Physics of Solids has developed a soft X-ray imaging technique for thicker magnets, closing this “thickness gap”. Their work reveals previously inaccessible 3D magnetic textures, and is an exciting development with a range of applications, including the study of naturally occurring magnetic rocks, transition-metal based permanent magnets for energy harvesting, and chiral magnets for spintronics.
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Image: (a) Schematic of the ptychography setup. (b) Ptychographic phase projections measured with RCP and LCP x rays, with the difference giving the XMCD signal, indicating the projection of the magnetization (anti)parallel to the x-ray beam.