Magnetic watermelon: Cr-doped core-shell Fe nanocluster.
We studied the nanostructure and magnetism by doping Cr into Iron/Iron-oxide core-shell nanoclusters (NCs) prepared by cluster deposition system at varied atomic percentages of Cr from 0 at.% to 8 at. %. The increase in coercive field and exchange bias field (Hex) has been reported below room temperature after the incorporation of Cr in the NCs. The formation of antiferromagnetic (AFM) Cr2O3 as a mixture with Fe-oxide shell causes the increase in Hex. The magnetic interactions in Fe NCs (~25 nm) can be controlled by AFM Cr-dopant. We report the origin of [??]-FeCr phase at very low Cr concentration (2 at. %) unlike in previous studies, and the interaction reversal from dipolar to exchange interaction in 8 at.% of Cr-doped core-shell NCs. With the inclusion of Cr in a core-shell system, [??]-FeCr originates as an intermetallic phase with bcc-Fe. The structural model of a Cr-doped core-shell NC looks like a watermelon, where the seeds of melon act like [??]-phase, spreading uniformly throughout the Fe-core (Fe pulp). The exchange coupling between the grains of [??]-FeCr and bcc-Fe at their grain boundaries play a significant role in controlling the net interaction.
Maninder Kaur and You Qiang
Department of Physics, University of Idaho, Moscow, ID 83844 USA
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|Title Annotation:||56TH ANNUAL SYMPOSIUM OF THE IDAHO ACADEMY OF SCIENCE: THEME: ENERGY, MATERIALS, AND NANOTECHNOLOGY|
|Author:||Kaur, Maninder; Qiang, You|
|Publication:||Journal of the Idaho Academy of Science|
|Date:||Dec 1, 2014|
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