Growth of two-dimensional patterns in the Fe-Cu multilayers driven far from equilibrium by ion irradiation

摘要

In the equilibrium immiscible Fe-Cu system, self-avoiding chains of ferromagnetic polycrystalline Fe grains were grown in the Fe_50Cu_50 multilayers after 200 keV xenon ion irradiation at room temperature to a dose of 5×10~15 Xe~+ cm~-2 and the chains featured self-simularity with a fractal dimension of 1.42. Increasing the irradiation dose up to 1×10~16 Xe~+ cm~-2 induced the Fe grains to organize themselves into a branching tee morphology with an increased fractal dimension of 1.88. In contrast, a new non-fractal pattern consisting of fcc Cu-rich grains was developed I the Fe_30Cu_70 multilayered films at An irradiation dose of 1×10~16 Xe~+ cm~-2 and was named as earthworm-like pattern.