Exploring the Interlayer Exchange Coupling of Ferromagnetic Films and Nanoclusters Across MgO

We investigate the interlayer exchange coupling (IEC) in Fe/MgO/Fe and Fe/MgO/Co systems. Samples are fabricated through molecular beam epitaxy (MBE) synthesis and magnetic properties are examined through magneto-optic Kerr effect (MOKE) measurements. First, comparing the bilinear coupling (J1) observed in the Fe/MgO/Fe and Fe/MgO/Co systems, we find an enhanced coupling in Fe/MgO/Co showing that J1 depends on magnetic material composition. Next, we embed Fe nanoclusters (NC) within the MgO spacer and find that we can tune the J1 by varying the position the NC. Lastly, examining J1 between ferromagnetic thin-film and NC in Fe/MgO/NC and Co/MgO/NC systems, we find a large enhancement in J1 for Co/MgO/NC with differences larger then what is seen in the analogous thin-film systems. This amplification provides evidence for enhanced coupling due to nano-scaling effects.