Interface mixing in Co/Cu: in situ electrical conductivity measurements on pulsed-laser-deposited multilayers

By providing the experimental possibility to monitor the electrical conductivity of metallic multilayers prepared by laser ablation during their growth in situ, information can be obtained on interface mixing effects. This is demonstrated for (5 nm Co/5 nm Cu)n multilayers ablated by a UHV–193 nm ArF–Pulsed Laser Deposition (PLD) system. Varying the laser fluence from 4.2 J cm-2 to 12.3 J cm-2 allows a corresponding variation of the fraction f of energetic particles within the ablated plume as well as of their average energy. As a result of such a bombardment-assisted deposition, mixing effects occur for both growth sequences, Co on top of Cu as well as Cu on top of Co. As expected, these mixing effects are most pronounced for high laser fluences and significantly decrease for fluences close to the ablation threshold. Comparison to TRIDYN Monte Carlo simulations allow one to extract estimates for the fraction f of energetic particles as well as for their average energy.