Magnetic and structural properties of laminated Co65Fe35 films

We report on coercivity mechanisms in Co₆₅Fe₃₅ films. Using a unique High Target Utilisation Sputtering System (HiTUS) sputtering system we have produced a range of samples with controlled grain size in the range 6-30 nm. This has enabled an evaluation of the effects of different seed layers (Ru, Cu, Ta and Mg) and the effects of lamination of the films. We found that in 100 Å single-layer films the coercivity rises abruptly from 29 to 90 Oe with grain size. We found that samples with Cu or Ru seed layers show the largest reduction in coercivity. The effects of lamination are more complex since it leads to a reduction in grain size whereas coercivity increases. We believe this is due to RKKY coupling through the metallic interlayers.