Suppressing anisotropy in nanostructured Fe/Ni superlattices with monolayer periodicity

We described here the growth of carefully engineered Fe/Ni(100) superlattices with monolayer periodicity (i.e., Fe50Ni50) on a Cu(100) crystalline substrate, nanostructured to 70 × 40 nm islands. The nanometer-thick, islanded Fe/Ni(100) superlattices are characterized in terms of composition, crystalline structure, and magnetic properties and show a magnetic behavior perfectly isotropic in-plane, with negligible effective anisotropy out of plane because the strongly reduced shape anisotropy due to the single-domain islands almost exactly compensates the perpendicular interfacial anisotropy due to the Fe/Ni layering. The suppression of anisotropy is achieved without nanolithography processes or in situ application of larger magnetic fields. The nanostructured films show a small coercivity [although 20 times larger than the ones grown on flat Cu(100) substrates]. The reduced shape anisotropy in the nanostructured superlattice accounts for the observed suppression of the effective anisotropy in-plane and out-of-plane.