The switching properties of patterned synthetic ferrimagnetic structures

摘要

We investigated the switching properties of patterned submicrometer synthetic ferromagnetic (SF) Ni65Fe15Co20(t(1) nm)/Ru 0.8 nm/Ni65Fe15Co20(t(2) nm) tri-layers. By changing t(1) and t(2), the shape anisotropy field, H(k)(sh)proportional tot(1)-t(2), was changed from 36 to 18 Oe, and the effective material anisotropy field, H-k(eff),proportional toalpha=(t(1)+t(2)/t(1)-t(2), was changed from 28 to over 60 Oe. We found that a hard axis field, H-hd, is less effective at reducing the easy axis switching field, H-sw, as alpha is increased, with alpha=3.7 requiring twice the relative magnitude of H-hd for the same relative reduction in H-sw as a single magnetic layer. In addition, by repeating the basic SF tri-layer structure in circular elements, we demonstrated improved stability against thermal activation by a factor of 2 with no associated increase in H-sw. (C) 2004 American Institute of Physics.