Microstructure, hydrogenation and optical behavior of Mg-Ni multilayer films deposited by magnetron sputtering

► The interdiffusion between Mg and Ni adjacent layers is seriously affected by the deposition temperature. ► The film deposited at 473 K exhibits amorphous/nanocrystalline composite structure. ► Without the Pd-cap catalysis layer, the film can still switch from metallic state to transparent state after hydrogenation. ► The optical transmittance modulation of the film reaches up to 19% in visible light region, and it nearly approaches the results of the Mg-Ni films with a Pd-cap layer.