Magnetoresistance and microstructure of sputtered Au–Co thin films

Abstract The magnetoresistance and microstructure of sputtered Au–Co thin films have been investigated. The thin films are prepared using RF sputtering system. Composite targets consisting of Au plate and Co chips are used. The film thickness is 15–100 nm. For Au–Co thin films of 50 nm thickness, the magnetoresistivity Δ ρ / ρ under 0–800 kA/m increases with increasing Co concentration, and reaches maximum value of 13.7% at Au–23 at% Co. Then the value decreases with increasing Co concentration. Δ ρ / ρ of 50 nm thick Au–23 at% Co thin films increases to 18.8% after annealing at 250°C. The half-width of the magnetoresistive response curve changes as a result of concentration and annealing conditions. This is due to the size and distribution change of Co fine particles, and change in the electron scattering of the Au matrix. The crystallographic relation FCC-Co(1 1 1)‖Au(1 1 1) is obtained between the Co particle and Au matrix.