Effect of microstructures on exchange anisotropy in Mn-Ir/Ni-Fe exchange-biased mutilayers with various stacking structures

The magnetic properties and the microstructures of the Mn-Ir/Ni-Fe multilayers with various stacking structures and buffer layer materials have been investigated. The (111) texture of Mn-Ir/Ni-Fe is obtained in the top structures with Ta or Zr buffer, However, all mutilayers which contain Mn-Ir films deposited on Ni-Fe films exhibit high H-ex regardless of the (111) preferred orientation of Mn-Ir film. The multilayers which show high H-ex have large Mn-Ir grains at the interface, compared with BS multilayers without exchange anisotropy. The multilayers which reveal the exchange anisotropy also have the grain-to-grain epitaxial tendency at interface of Mn-Ir/Ni-Fe. It is concluded that the H-ex is not related to the (111) texture of the Mn-Ir film, but related to the grain size of the Mn-Ir film and the morphology at the interface between the Mn-Ir and the Ni-Fe grains.