Tuning Exchange Bias and Coercive Fields in Ferromagnet/Antiferromagnet Bilayers with Ion Irradiation
Date
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
The effect of He ion irradiation on the magnetic properties of NiFe exchange coupled to different antiferromagnetic alloys (FeMn, CrMn, and PtMn) with the same layer thickness is investigated. All systems exhibit an enhanced coercivity prior to irradiation. An exchange bias field is only observed for FeMn and PtMn. Upon ion irradiation the FeMn-based system shows with increasing ion dose an enhancement followed by a decrease and finally a full suppression of the exchange bias field. For systems exchange coupled to PtMn only a decrease and suppression of the bias field is found. This can be attributed to the ion induced chemical disordering of the antiferromagnetic phase in the latter case. In the case of CrMn the antiferromagnetic layer thickness is too small to induce an exchange bias field, but an enhanced coercivity is observed which is caused by the exchange coupling between the antiferromagnetic and ferromagnetic layers. For all systems, this enhanced coercivity of the exchange coupled bilayer system is modified by ion irradiation.