Effects of an Os layer on the magnetic properties of CoFe∕IrMn

Abstract

The uses of Os as an antidiffusion and buffer layer in IrMn exchange coupled CoFe film were investigated. For the purpose of antidiffusion, the inserted Os layer showed a distinct improvement of S>0.9, with HC slightly increasing by 1.6 times for the CoFe∕Os∕MnOs multilayer after 400 °C annealing, even though the Os thickness was as thin as 0.3 nm. Furthermore, with a 0.3 nm Os barrier, the 350 °C annealed CoFe∕Os∕IrMn∕CoFe showed almost the same magnetic behavior as the as-deposited state, while the Hex of the upper part of the CoFe∕Os∕IrMn changed from 100 to 190 Oe. In addition, as a buffer layer, the Os buffer layer could enhance the diffraction peak intensities of IrMn(111)∕Os(002) and CoFe (111), and the Hex of CoFe∕IrMn was proportional to the Os thickness. A 120 Oe of Hex was achieved by using an 11 nm Os buffer layer in a CoFe10nm∕IrMn15nm bottom type film. These results show that Os has the potential to be an antidiffusion and buffer layer in a magnetic multilayer.