Thermal stability of nanometer range Ti/Ni multilayers

Abstract

Thermal stability of equidistant nanometer (nm) range Ti/Ni multilayer (ML) structures have been studied to investigate the interfacial microstructural changes upon thermal annealing. Two different ML having bilayer periodicity 10 nm, i.e., [Ti(5 nm)/Ni(5 nm)]10 and 6 nm, i.e., Ti(3 nm)/Ni(3 nm)]10 were prepared under ultra high vacuum deposition condition. It was observed that when the bilayer periodicity is changed from 10 nm to 6 nm, the individual layers grow in an amorphous form as compared to poly-crystalline layers of the former. The X-ray diffraction measurements show significantly different changes in the structural properties of the two ML. Moreover, the interdiffusion measurements carried out on both the ML, using X-ray reflectivity technique indicates slower inter-diffusion in case of samples having smaller periodicity. The hysteresis measurements on a ML with 10 nm periodicity show a drastic change in the magnetization behavior of the sample when annealed at or above 300 °C. The observed magnetization behavior is explained on the basis of structural and chemical changes that have occurred at the interface due to the thermal treatment.