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

Date
2014-11-13
Authors
Malik, V.
Goodwill, J.
Mallapragada, Surya
Prozorov, Tanya
Prozorov, Ruslan
Journal Title
Journal ISSN
Volume Title
Publisher
Altmetrics
Authors
Research Projects
Organizational Units
Ames Laboratory
Organizational Unit
Physics and Astronomy
Organizational Unit
Journal Issue
Series
Abstract

The rate of heating of 15 nm uniformly-sized magnetic aqueous nanoparticles suspension by high-amplitude and high-frequency ac magnetic field induced by the resonating LC circuit 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 of a frozen colloid by fitting field-dependent magnetization to a 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.

Description
Keywords
Nanoparticles, Magnetic hysteresis, Saturation magnetization, Magnetic moments, Magnetometers, Specific absorption rate
Citation
DOI
Collections