Long-range order on the atomic scale induced at CoFeB/MgO interfaces

The amorphous (a-) CoFeB/crystalline (c-) MgO based tunneling system interface has been studied by means of quantitative high resolution transmission electron microscopy from atomic to micrometer length scales with increasing annealing temperatures. On the micron scale an irregular nucleation is found. On the atomic scale a long-range order is induced by the MgO interface, explaining the high tunnel magnetoresistance values > 100% even for not fully crystallized CoFeB/MgO/CoFeB tunnel junctions.