Microstructural studies of top and bottom magnetic tunnel junctions

High-resolution electron microscopy has been used to study the microstructu ral properties of top and bottom magnetic tunnel junctions. Different physi cal properties have been found for the two configurations, and they have be en interpreted in terms of microstructural features. All physical parameter s favor the bottom configuration except for the coupling field, which is hi gher for the bottom structure. This latter result has been explained by the more pronounced roughness at the interfaces between the electrodes and the insulator film. (C) 2001 American Institute of Physics.