Exchange bias and its thermal stability in ferromagnetic/antiferromagnetic antidot arrays

摘要

The exchange bias (EB) effect and its thermal stability in nanoscale Co/NiO antidot arrays and sheet films have been investigated. The EB field H_E increases with increasing Co thickness (t_(Co) and reaches a maximum at t_(Co)= 8 nm in the antidot arrays, whereas HE decreases with t_(Co) in the sheet films. Compared with the sheet films, HE in the antidot arrays is either enhanced or decreased, depending on the thickness of the ferromagnetic Co layer, which is due to the three-dimensional effects in the antiferromagnetic NiO and ferromagnetic Co layers caused by the nanopores. A higher thermal stability is observed in the antidot arrays due to the out-of-plane anisotropy constant K_1 of the misaligned antiferromagnetic magnetization component.