Enhanced Exchange Bias In Sub-50-nm Irmn/cofe Nanostructure

摘要

The exchange bias field (H_(ex)) of IrMn/CoFe deposited on a large-area nanoporous anodized alumina (AAO) is tailored by varying the pore density (D) and the network width (w) of AAO. The H_(ex) increases with increasing D and reaches its maximum at D = 5.6 × 10~(10) cm~(-2) and w～28 nm. The enhancement in H_(ex), twice larger than that of the continuous film, is attributed to the reduction in antiferromagnetic (AFM) and ferromagnetic (FM) domain sizes. The suppression of H_(ex) is observed for further increase in D, which may result from the excessive misalignment of AFM and FM spins and weakened AFM anisotropy.