New interface solution for Ni/Ti multilayers

Nickel/titanium multilayers (ML) and supermirrors (SM) were fabricated by DC magnetron sputtering on glass or Si (1 0 0) substrates. It was possible to increase the reflectivity of ML and SM by the deposition of an ultrathin Cr layer at the Ni/Ti interfaces. Interdiffusion decreases when the Ni and Ti are separated by a covering Cr layer (3 Å), whereas, in the range where the Cr interlayer thickness is higher than the Ni/Ti interdiffusion depth (approximately 6 Å) or the surface roughness, the growth of a closed Cr layer is prohibited reducing the reflectivity. The presence of a 10 Å Cr interlayer on some Ti layers also results in enhanced reflectivities due to a smoothing effect of the interface for the following layers. The reflectivities of two monochromators for qz=0.069Å and a bandwidth (Δλ/λ) of 6% and 12% reach a value of approximately 0.90.