Atomistic simulations of low energy ion assisted vapor deposition of metalmultilayers

The properties of giant magnetoresistance multilayers are a sensitive funct ion of the vapor deposition process used for their synthesis. The highest m agnetoresistance 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 t he physical vapor deposition of Ni/Cu/Ni multilayers grown in the [111] dir ection from thermalized metal fluxes characteristic of molecular beam epita xy. The simulations indicated that the roughness of the interfaces was sign ificantly 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-ni ckel intermixing at the nickel on copper interface. Interface flattening wi thout intermixing could be achieved using a modulated low energy ion assist ance strategy in which the first half of each new material layer was deposi ted 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 prom ising approach for creating metal multilayers with improved magnetoresistan ce. (C) 2000 American Institute of Physics. [S0021-8979(00)08804-6].