Magnetic response of hybrid ferromagnetic and antiferromagnetic core–shell nanostructures

Abstract

The synthesis of FeTiO₃–Ni(Ni₈₀Fe₂₀) core–shell nanostructures by a two-step method (sol–gel and DC electrodeposition) has been demonstrated. XRD analysis confirms the rhombohedral crystal structure of FeTiO₃(FTO) with space group R. Transmission electron microscopy clearly depicts better morphology of nanostructures with shell thicknesses of ∼25 nm. Room temperature magnetic measurements showed significant enhancement of magnetic anisotropy for the permalloy (Ni₈₀Fe₂₀)–FTO over Ni–FTO core–shell nanostructures. Low temperature magnetic measurements of permalloy–FeTiO₃ core–shell structure indicated a strong exchange bias mechanism with magnetic coercivity below the antiferromagnetic Neel temperature (T_N = 59 K). The exchange bias is attributed to the alignment of magnetic moments in the antiferromagnetic material at low temperature. Our scheme opens a path towards optimum automotive systems and wireless communications wherein broader bandwidths and smaller sizes are required.