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Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Exchange bias and Verwey transition in Fe5C2/Fe3O4 core/shell nanoparticles
M Xing1, Jeotikanta Mohapatra1, J Elkins1
1Department of Physics, The University of Texas at Arlington, Arlington, Texas 76019, USA. pliu@uta.edu.
Abstract:
This report presents new findings of exchange bias and related structural and magnetic properties in iron carbide/magnetite (Fe5C2/Fe3O4) core/shell nanoparticles. The exchange bias emerges from an energetic landscape, namely a first-order phase transition-the Verwey transition at 125 K, during which the Fe3O4 shell changes from the cubic to monoclinic structure. The phase transition leads to the exchange bias because it results in abrupt changes in magnetocrystalline anisotropy and exchange coupling. Another unique phenomenon identified in this composite system is enhanced magnetic coercivity due to the uniaxial anisotropy of the monoclinic phase. An analysis of the correlations between the observed phenomena is given based on the temperature dependence of the coercivity, the exchange bias field values, and the Verwey transition temperature.
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