Magnetic interaction reversal in watermelon nanostructured Cr-doped Fe nanoclusters

Cr-doped core-shell Fe/Fe-oxide nanoclusters (NCs) were synthesized at varied atomic percentages of Cr from 0 at.% to 8 at.%. The low concentrations of Cr (<10 at.%) were selected in order to inhibit the complete conversion of the Fe-oxide shell to Cr2O3 and the Fe core to FeCr alloy. The magnetic interaction in Fe/Fe-oxide NCs (~25 nm) can be controlled by antiferromagnetic Cr-dopant. We report the origin of σFeCr phase at very low Cr concentration (2 at.%) unlike in previous studies, and the interaction reversal from dipolar to exchange interaction in watermelon-like Cr-doped core-shell NCs.