Interfacial structures of Ni/Ti multilayers studied by magneto-optical andoptical spectroscopies and by X-ray diffraction

Interfacial structures of Ni/Ti multilayered films (MLF) were studied by us ing experimental and computer-simulated magneto-optical (MO: equatorial Ker r effect) and optical spectroscopies. A series of Ni/Ti MLF with bilayer pe riods of 0.5-30 nm, a constant sublayer thickness ratio of 1:1, and a total thickness of 330 nm were prepared by using computer-controlled double-pair target face-to-face sputtering onto glass substrates at room temperature. The computer simulation was performed by solving the multireflection proble m with a matrix method, assuming either sharp interfaces resulting in recta ngular depth profiles of the components or mixed interfaces of variable thi ckness between pure metal sublayers. The existence of a threshold nominal N i-sublayer thickness of about 3 nm for observing the equatorial Kerr effect in the as-deposited Ni/Ti MLF is explained by the formation of a nonmagnet ic Ti-Ni alloy in the interfacial region during the deposition. Annealing t he Ni/Ti MLF at 580 K for 60 min caused a solid-state reaction which increa sed the volume fraction of the amorphous (or disordered) Ni-Ti alloy phase in the Ni/Ti MLF. The obtained result were confirmed by the x-ray diffracti on data.