Hybrid X-ray mirror coatings: a pioneer approach to enable focusing beyond 80 keV

Focusing high-energy photons above 80 keV remains a significant challenge due to the absorption edges of conventional high-Z thin film materials such as W, Ir, Pt, and Au, which lead to substantial reflectance losses above this energy. In this work, we introduce a novel approach, to our knowledge, for fabrication of Ni-based thin film multilayers, deposited by DC magnetron sputtering, offering efficient reflection of photon energies beyond 80 keV. These coatings were characterized using XRR at 8.048 keV with a laboratory X-ray source and at synchrotron beamlines. Structural and morphological characterization of the layers was carried out by STEM and XPS. Furthermore, we produced depth-graded multilayers of Ni and W and successfully integrated them into hybrid structures, advancing a concept originally proposed for focusing light up to the sub-MeV range. These promising results have applications not only in astronomical telescope optics but also in synchrotron beamline instrumentation.