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Title: Tuning exchange bias in Fe/γ-Fe{sub 2}O{sub 3} core-shell nanoparticles: Impacts of interface and surface spins

A comparative study has been performed of the exchange bias (EB) effect in Fe/γ-Fe{sub 2}O{sub 3} core-shell nanoparticles with the same thickness of the γ-Fe{sub 2}O{sub 3} shell (∼2 nm) and the diameter of the Fe core varying from 4 nm to 11 nm. Transmission electron microscopy (TEM) and high-resolution TEM confirmed the high quality of the core-shell nanostructures. A systematic analysis of magnetization versus magnetic field measurements under zero-field-cooled and field-cooled regimes using the Meiklejohn-Bean model and deconvoluting superparamagnetic and paramagnetic contribution to the total magnetic moment Langevin function shows that there exists a critical particle size (∼10 nm), above which the spins at the interface between Fe and γ-Fe{sub 2}O{sub 3} contribute primarily to the EB, but below which the surface spin effect is dominant. Our finding yields deeper insight into the collective contributions of interface and surface spins to the EB in core-shell nanoparticle systems, knowledge of which is the key to manipulating EB in magnetic nanostructures for spintronics applications.
Authors:
; ; ;  [1]
  1. Department of Physics, University of South Florida, Tampa, Florida 33620 (United States)
Publication Date:
OSTI Identifier:
22283125
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 104; Journal Issue: 7; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 77 NANOSCIENCE AND NANOTECHNOLOGY; INTERFACES; IRON; IRON OXIDES; MAGNETIC FIELDS; MAGNETIC MOMENTS; MAGNETIZATION; NANOSTRUCTURES; PARAMAGNETISM; PARTICLE SIZE; PARTICLES; SPIN; SUPERPARAMAGNETISM; SURFACES; TRANSMISSION ELECTRON MICROSCOPY