49th Magnetic Materials Center Seminar
June 29, 2007, 9:00
7th floor seminar room, Sengen
Structural characterization of magnetic multilayer thin films using three dimensional atom probe (3DAP)
C.Y. You
As a result of the very fine structures of magnetic multilayer thin films, the microstructure-property relationships of these films are less understood, and require a three-dimensional microscopy technique with high spatial resolution. Three-dimensional atom probe (3DAP) analysis has subnanometer spatial resolution and single-atom sensitivity, and has been used to characterize multilayer thin films such as giant magnetoresistance (GMR), tunnelling magnetoresistance (TMR) structures and quantum well structure.
In this talk, the ways of making a 3DAP samples from a film structure will be reviewed, including posts making, focus ion milling, field ion microscopy, and sputtering. One example of analysis of giant magnetoresistance (GMR) structure containing a nano-oxide layer (NOL) incorporated into Cu spacer layer will be demonstrated. It was found that the morphology of the NOL changes from a planar layer to discrete particles on annealing, indicating the dominance of surface energy on the morphology evolution. Direct evidence was obtained for significant Mn diffusion from the IrMn antiferromagnetic layer and partitioning to the oxide region during annealing.