Microstructural and micromagnetic characterization of thin film magnetic tunnel junctions

High-resolution electron microscopy, Lorentz microscopy, and off-axis elect ron holography have been used to characterize magnetic tunnel junctions. Ob servations in cross section show that the tunnel barriers are slightly narr ower and smoother after annealing at temperatures up to 350 degrees C. The demagnetization of a magnetically hard CoPtCr reference layer through repea ted magnetization reversal of a soft layer of either Co or Ni40Fe60 is like ly to originate from magnetic fringing fields at Neel walls, which form in the soft layers close to the coercive field. (C) 1999 American Institute of Physics. [S0021-8979(99)61308-1].