Structural and magnetic properties studies on swift heavy ion (SHI) irradiated Fe_3O_4 thin films

摘要

Polycrystalline Fe_3O_4 thin films are synthesized at low temperature by electroless plating, and the effects of irradiation by Kr~(26+) ions at energy of 2.03 GeV on the magnetic properties of the Fe_3O_4 thin films are investigated by macroscopic magnetization measurements (vibrating sample magnetometer, VSM; superconducting quantum interference device, SQUID) and microscopic distribution of the magnetic moments (conversion electron mossbauer spectroscopy, CEMS) as well as magnetic domain structure (magnetic force microscope, MFM) analyses. The initial crystallographic structure of the Fe_3O_4 remains unaffected after swift heavy ion (SHI) irradiation at low damage levels, but VSM, CEMS and MFM results indicate that SHI irradiation is an effectual tool to not only modify the macro-magnetic properties (saturation magnetization, coercivity, etc.), but also modify the micro-magnetic properties (magnetic anisot-ropy, distribution of the magnetic moments, magnetic domain structure, etc.) significantly. And all modifications of these properties could be interpreted very well by the effects related to the stress and defects (the production, accumulation and free) induced by SHI irradiation.