Magnetic properties of antidots in conventional and spin-reoriented antiferromagnetically coupled layers

Antiferromagnetically coupled (AFC) patterned media technology is one approach to reduce dipolar interactions and thus minimize the switching field distribution (SFD) in bit-patterned media. Achieving anti-parallel alignment of magnetic moments at remanence requires a large exchange coupling field (H _ex), especially in patterned nanostructures, which exhibit a large enhancement in coercivity after patterning. In our work, we observed a very high H _ex of more than 15 kOe in Co thin film antiferromagnetically coupled to (Co/Pd) multilayers with a high perpendicular magnetic anisotropy (PMA). In contrast, an H _ex of only 380 Oe was measured in the case of (Co/Pd) multilayers of the type [Co (0.4 nm)/Pd (0.8 nm)] ₃ antiferromagnetically coupled with (Co/Pd) multilayers with a high PMA. The effect of H _ex on SFD of patterned structures was investigated, and it was found that SFD can be reduced in AFC patterned films with a high H _ex.