Strongly exchange coupled inverse ferrimagnetic soft/hard, Mn(x)Fe(3-x)O4/Fe(x)Mn(3-x)O4, core/shell heterostructured nanoparticles.
Inverted soft/hard, in contrast to conventional hard/soft, bi-magnetic core/shell nanoparticles of Mn(x)Fe(3-x)O(4)/Fe(x)Mn(3-x)O(4) with two different core sizes (7.5 and 11.5 nm) and fixed shell thickness (∼0.6 nm) have been synthesized. The structural characterization suggests that the particles have an interface with a graded composition. The magnetic characterization confirms the inverted soft/hard structure and evidences a strong exchange coupling between the core and the shell. Moreover, larger soft core sizes exhibit smaller coercivities and loop shifts, but larger blocking temperatures, as expected from spring-magnet or graded anisotropy structures. The results indicate that, similar to thin film systems, the magnetic properties of soft/hard core/shell nanoparticles can be fine tuned to match specific applications.
CIN2(ICN-CSIC) and Universitat Autònoma de Barcelona, Catalan Institute of Nanotechnology, Campus de la UAB, 08193 Bellaterra (Barcelona), Spain.
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López-Ortega
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Estrader
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Salazar-Alvarez
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Estradé
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Golosovsky
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Dumas
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Keavney
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Vasilakaki
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Trohidou
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Sort
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Peiró
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Suriñach
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Baró
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