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Title: Comparative Study of Magnetic Properties of Nanoparticles by High-Frequency Heat Dissipation and Conventional Magnetometry

The rate of heating of a water-based colloid of uniformly sized 15 nm magnetic nanoparticles by high-amplitude and high-frequency ac magnetic field induced by the resonating LC circuit (nanoTherics Magnetherm) was measured. The results are analyzed in terms of specific energy absorption rate (SAR). Fitting field amplitude and frequency dependences of SAR to the linear response theory, magnetic moment per particles was extracted. The value of magnetic moment was independently evaluated from dc magnetization measurements (Quantum Design MPMS) of a frozen colloid by fitting field-dependent magnetization to Langevin function. The two methods produced similar results, which are compared to the theoretical expectation for this particle size. Additionally, analysis of SAR curves yielded effective relaxation time.
Authors:
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Publication Date:
OSTI Identifier:
1221934
Report Number(s):
IS-J--8775
Journal ID: ISSN 1949-307X; TRN: US1500749
Grant/Contract Number:
AC02-07CH11358
Type:
Accepted Manuscript
Journal Name:
IEEE Magnetics Letters
Additional Journal Information:
Journal Volume: 5; Journal ID: ISSN 1949-307X
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY