Correlation among exchange coupling, surface roughness and junction size in magnetic tunnel junctions

Abstract Magneto-optic Kerr Effect, atomic force microscopy and magnetoresistance measurements have been carried out on as-deposited and annealed magnetic tunnel junctions with junction sizes 180, 250, 320 and 380 μm in order to investigate the correlation among interlayer exchange coupling, surface roughness and junction size. The interlayer exchange coupling ( H E ) shows very good correlation with surface roughness across the junction in agreement with Neel's orange peel coupling. The normalized H E and H c values are constant over the junction in larger junctions while tunneling magnetoresistance ratios generally improve with increasing junction size.