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Building Nanocomposite Magnets by Coating a Hard Magnetic Core with a Soft Magnetic Shell
Author(s) -
Liu Fei,
Zhu Jinghan,
Yang Wenlong,
Dong Yunhe,
Hou Yanglong,
Zhang Chenzhen,
Yin Han,
Sun Shouheng
Publication year - 2014
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201309723
Subject(s) - materials science , magnet , coercivity , nanocomposite , magnetism , nanoparticle , magnetic nanoparticles , coating , nanotechnology , fabrication , exchange bias , tetragonal crystal system , phase (matter) , condensed matter physics , composite material , magnetic anisotropy , magnetization , magnetic field , chemistry , mechanical engineering , physics , medicine , alternative medicine , organic chemistry , pathology , quantum mechanics , engineering
Controlling exchange coupling between hard magnetic and soft magnetic phases is the key to the fabrication of advanced magnets with tunable magnetism and high energy density. Using FePt as an example, control over the magnetism in exchange‐coupled nanocomposites of hard magnetic face‐centered tetragonal (fct) FePt and soft magnetic Co (or Ni, Fe 2 C) is shown. The dispersible hard magnetic fct‐FePt nanoparticles are first prepared with their coercivity ( H c ) reaching 33 kOe. Then core/shell fct‐FePt/Co (or Ni, Fe 2 C) nanoparticles are synthesized by reductive thermal decomposition of the proper metal precursors in the presence of fct‐FePt nanoparticles. These core/shell nanoparticles are strongly coupled by exchange interactions and their magnetic properties can be rationally tuned by the shell thickness of the soft phase. This work provides an ideal model system for the study of exchange coupling at the nanoscale, which will be essential for building superstrong magnets for various permanent magnet applications in the future.