Microstructures of Co/Cr bilayer films epitaxially grown on MgO single-crystal substrates

Microstructures of Co/Cr bilayer films epitaxially grown on MgO (100) and (110) single-crystal substrates have been studied by high-resolution transmission electron microscopy. The bicrystalline Co layer formed on the MgO (100) substrate contains a number of (0001) stacking faults. The single-crystal Co layer formed on the MgO (110) substrate consists of slightly misoriented subgrains, grown on (211)-oriented Cr domains. Dislocations and lattice strain are observed at the Cr/MgO (110) interface. The misorientations and the defects are thought to be introduced to accommodate the large lattice mismatch of about -16% in the MgO [1¯10] direction at the Cr/MgO (110) interface.