Correlating antiferromagnetic spin structures with ion-beam bombardment in exchange-biased NiFe/Mn bilayers

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 (V(EH) 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, H(ex), with increasing V(EH) suggests strongly that the Ar ion-beam bombardment process may create uncompensated Mn spins (H(ex) enhancement) or increase the spin misalignment in ferromagnet (FM)/antiferromagnet (AF) interfaces (H(ex) decrease), depending on the energy used. A schematic FM/AF spin structure was proposed to explain this unusual exchange bias behavior. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3063661]