Scientists from the Institute of Physics, Polish Academy of Sciences in Warsaw, while optimizing the structure of MBE grown magnetic multilayered systems, have found that Au deposited on a Mo(110) surface at elevated temperatures self-assembles as epitaxial islands measuring several dozen nanometres in the lateral dimension. The team suddenly realized that such a patterned buffer may spatially modify the magnetization orientation in the deposited Co ultrathin layer. The researchers found that the Co layer grown on the Au islands is magnetized perpendicularly to the film plane whereas the magnetization of the part deposited between the islands is aligned in the sample plane. As a result, the researchers have obtained an array of elevated perpendicularly magnetized dots wrapped by a trench matrix with in-plane magnetization.

A deep understanding of the island growth is desirable as the dimensions of the Au islands directly determine the size of magnetic dots. The surface energies, the mechanisms of the surface diffusion and the interlayer mass transport depending on the growth temperature as well as the amount of deposited material affect the basic parameters characterizing the Au islands, including shape, height, area and surface density. Also the relationship between the crystallographic orientations at the Mo/Au interface and the strains arising from the lattice mismatch substantially influence the island-like growth.

The researchers presented their work in the journal Nanotechnology.