X-ray Reflectivity and Polarized Neutron Reflectivity Investigations of $[Co_{60}Fe_{60}B_{20}//MgO]_n$ Multilayers

In recent years magnetic tunnel junctions have been intensively studied and incorporated in magnetic random access memory devices and magnetic sensors, where large tunnelling magnetoresistance ratios are preferred. The largest tunnelling magnetoresistance values until now have been observed in magnetic tunnel junctions with MgO barriers and CoFeB electrodes after annealing of the junction above the recrystallization temperature of the amorphous CoFeB layers. We used X-ray reflectivity and polarized neutron reflectivity to study [Co_{60}Fe_{60}B_ {20}//MgO]_{x14} multilayers with the MgO layers prepared by different methods and annealed at different temperatures in order to compare the interface quality and the structural changes induced upon annealing.