Preparation of barium ferrite dot arrays by means of nano-spot crystallization

Abstract

A novel process to prepare hexagonal ferrite films with dot arrays has been proposed. Two immiscible elements, Al and Si, were first deposited onto a Si (1 1 1) substrate at various temperatures. The microstructure of this kind of film depends on the concentration and deposition temperature. Scanning electron microscopy (SEM) results show that structures with Al dot arrays, in the size range of 30–50 nm, embedded into an amorphous Si matrix can be obtained by precise control of the sputtering conditions. Amorphous Ba–Fe–O films were deposited onto the dot array films at room temperature and then annealed to crystallize in part. Experimental results indicate that amorphous Ba–Fe–O films on Al dots can be crystallized by flash annealing the samples at 700 °C for 60 s. However, those on the amorphous Si keep the amorphous state. A structure with magnetic dot arrays embedded into a nonmagnetic matrix has been achieved by this process. The magnetic properties of the samples have been discussed.