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Title: Exchange bias in Fe/Fe{sub 3}O{sub 4} core-shell magnetic nanoparticles mediated by frozen interfacial spins.

Abstract

The magnetization curves of monodisperse Fe/Fe{sub 3}O{sub 4} core-shell and Fe{sub 3}O{sub 4} hollow-shell nanoparticles reveal an unusual exchange-bias effect. Hysteresis measurements of core-shell particles at 5 K after field cooling exhibit a large loop shift associated with unidirectional anisotropy whereas Fe{sub 3}O{sub 4} hollow-shell nanoparticles support much smaller shifts. Both core-shell and hollow-shell particles exhibit sharp demagnetization jumps at low fields associated with a sudden switching of shell moments. Temperature-dependent magnetization of core-shell particles at high fields shows a deviation between field-cooled and zero-field-cooled curves below 30 K, suggesting the presence of frozen spins at the interface. These frozen interfacial spins play an important role in mediating the exchange coupling between the ferromagnetic core and ferrimagnetic shell.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC); National Science Foundation (NSF)
OSTI Identifier:
979550
Report Number(s):
ANL/CNM/JA-63367
Journal ID: ISSN 1098-0121; TRN: US201010%%764
DOE Contract Number:  
DE-AC02-06CH11357
Resource Type:
Journal Article
Journal Name:
Phys. Rev. B
Additional Journal Information:
Journal Volume: 80; Journal Issue: Oct. 2009; Journal ID: ISSN 1098-0121
Country of Publication:
United States
Language:
ENGLISH
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANISOTROPY; DEMAGNETIZATION; HYSTERESIS; MAGNETIZATION

Citation Formats

Ong, Q. K., Wei, A., Lin, X.-M., Center for Nanoscale Materials, and Purdue Univ. Exchange bias in Fe/Fe{sub 3}O{sub 4} core-shell magnetic nanoparticles mediated by frozen interfacial spins.. United States: N. p., 2009. Web. doi:10.1103/PhysRevB.80.134418.
Ong, Q. K., Wei, A., Lin, X.-M., Center for Nanoscale Materials, & Purdue Univ. Exchange bias in Fe/Fe{sub 3}O{sub 4} core-shell magnetic nanoparticles mediated by frozen interfacial spins.. United States. doi:10.1103/PhysRevB.80.134418.
Ong, Q. K., Wei, A., Lin, X.-M., Center for Nanoscale Materials, and Purdue Univ. Thu . "Exchange bias in Fe/Fe{sub 3}O{sub 4} core-shell magnetic nanoparticles mediated by frozen interfacial spins.". United States. doi:10.1103/PhysRevB.80.134418.
@article{osti_979550,
title = {Exchange bias in Fe/Fe{sub 3}O{sub 4} core-shell magnetic nanoparticles mediated by frozen interfacial spins.},
author = {Ong, Q. K. and Wei, A. and Lin, X.-M. and Center for Nanoscale Materials and Purdue Univ.},
abstractNote = {The magnetization curves of monodisperse Fe/Fe{sub 3}O{sub 4} core-shell and Fe{sub 3}O{sub 4} hollow-shell nanoparticles reveal an unusual exchange-bias effect. Hysteresis measurements of core-shell particles at 5 K after field cooling exhibit a large loop shift associated with unidirectional anisotropy whereas Fe{sub 3}O{sub 4} hollow-shell nanoparticles support much smaller shifts. Both core-shell and hollow-shell particles exhibit sharp demagnetization jumps at low fields associated with a sudden switching of shell moments. Temperature-dependent magnetization of core-shell particles at high fields shows a deviation between field-cooled and zero-field-cooled curves below 30 K, suggesting the presence of frozen spins at the interface. These frozen interfacial spins play an important role in mediating the exchange coupling between the ferromagnetic core and ferrimagnetic shell.},
doi = {10.1103/PhysRevB.80.134418},
journal = {Phys. Rev. B},
issn = {1098-0121},
number = Oct. 2009,
volume = 80,
place = {United States},
year = {2009},
month = {10}
}