Atomistic simulations of low energy ion assisted vapor deposition of metal multilayers

The properties of giant magnetoresistance multilayers are a sensitive function of the vapor deposition process used for their synthesis. The highest magnetoresistance occurs when deposition results in interfaces that are flat and chemically separated. Molecular dynamics simulations have been used to explore the potential benefits of low energy xenon ion assistance during the physical vapor deposition of Ni/Cu/Ni multilayers grown in the @111# direction from thermalized metal fluxes characteristic of molecular beam epitaxy. The simulations indicated that the roughness of the interfaces was significantly reduced as the ion energy was increased from 0 to 5 eV. However, increasing the ion energy above 2 eV also resulted in significant copper–nickel intermixing at the nickel on copper interface. Interface flattening without intermixing could be achieved using a modulated low energy ion assistance strategy in which the first half of each new material layer was deposited without ion assistance, while the remainder of the layer was deposited with an optimum low ion energy assistance of 4 eV. Modulated low energy ion assistance during thermalized metal atom deposition was found to be a promising approach for creating metal multilayers with improved magnetoresistance. © 2000 American Institute of Physics. @S0021-8979~00!08804-6#