Soft x-ray microscopy with 7 nm resolution
Benedikt Rösner, Simone Finizio, Frieder Koch, Florian Döring, Vitaliy A. Guzenko, Manuel Langer, Eugenie Kirk, Benjamin Watts, Markus R. Meyer, Joshua Loroña Ornelas, Andreas Späth, Stefan Stanescu, Sufal Swaraj, Rachid Belkhou, Takashi Ishikawa, Thomas F. Keller, B. Gross, Martino Poggio, R. Fink, Jörg Raabe, Armin Kleibert, Christian Dávid
Abstract
The availability of intense soft x-ray beams with tunable energy and polarization has pushed the development of highly sensitive, element-specific, and noninvasive microscopy techniques to investigate condensed matter with high spatial and temporal resolution. The short wavelengths of soft x-rays promise to reach spatial resolutions in the deep single-digit nanometer regime, providing unprecedented access to magnetic phenomena at fundamental length scales. Despite considerable efforts in soft x-ray microscopy techniques, a two-dimensional resolution of 10 nm has not yet been surpassed in direct imaging. Here, we report on a significant step beyond this long-standing limit by combining newly developed soft x-ray Fresnel zone plate lenses with advanced precision in scanning control and careful optical design. With this approach, we achieve an image resolution of 7 nm. By combining this highly precise microscopy technique with the x-ray magnetic circular dichroism effect, we reveal dimensionality effects in an ensemble of interacting magnetic nanoparticles. Such effects are topical in current nanomagnetism research and highlight the opportunities of high-resolution soft x-ray microscopy in magnetism research and beyond.