Abstract
The correlation between the ion-beam bombardment and the exchange bias magnetism in NiFe (10 nm)/Mn (25 nm) bilayers was studied. While the bottom Mn layers bombarded by different Ar ion-beam energies (VEH from 70 to 150 V) retained the same structure, significant differences in exchange bias were observed when in contact with a top NiFe layer. The dependence of the exchange bias field, Hex, with increasing VEH suggests strongly that the Ar ion-beam bombardment process may create uncompensated Mn spins (Hex enhancement) or increase the spin misalignment in ferromagnet (FM)/antiferromagnet (AF) interfaces (Hex decrease), depending on the energy used. A schematic FM/AF spin structure was proposed to explain this unusual exchange bias behavior. © 2009 American Institute of Physics.