An MTJ consists of two magnetic layers separated by a thin insulating layer. For magnetic layers that have large spin polarizations, large resistance changes occur through the junction when the moments of the magnetic layers switch from a parallel to an anti-parallel alignment. The first observation of MR in an all-oxide MTJ was for a La0.67
junction, in which an MR of 83% was observed at 4Â
K (FigureÂ 6.12
) (Lu etÂ al., 1996
). Further structural improvements to the quality of the heterostructure and the addition of a CoO top pinning layer increased the MR of these MTJs to as high as 1850% at 4Â
K, corresponding to a spin ...