Skip to main content
Article
A Method for Measuring the Néel Relaxation Time in a Frozen Ferrofluid
Journal of Applied Physics
  • Ronald J Tackett, Kettering University
  • Jagdish Thakur, Wayne State University
  • Nathaniel Mosher, Kettering University
  • Emily Perkins-Harbin, Kettering University
  • Ronald E Kumon, Kettering University
  • Lihua Wang, Kettering University
  • Corneliu Rablau, Kettering University
  • Prem P Vaishnava, Kettering University
Document Type
Article
Publication Date
8-1-2015
Abstract

We report a novel method of determining the average Néel relaxation time and its temperature dependence by calculating derivatives of the measured time dependence of temperature for a frozen ferrofluid exposed to an alternating magnetic field. The ferrofluid, composed of dextran-coated Fe3O4 nanoparticles (diameter 13.7 nm ± 4.7 nm), was synthesized via wet chemical precipitation and characterized by x-ray diffraction and transmission electron microscopy. An alternating magnetic field of constant amplitude (H0=20H0=20 kA/m) driven at frequencies of 171 kHz, 232 kHz, and 343 kHz was used to determine the temperature dependent magnetic energy absorption rate in the temperature range from 160 K to 210 K. We found that the specific absorption rate of the ferrofluid decreased monotonically with temperature over this range at the given frequencies. From these measured data, we determined the temperature dependence of the Néel relaxation time and estimate a room-temperature magnetocrystalline anisotropy constant of 40 kJ/m3, in agreement with previously published results.

Disciplines
DOI
10.1063/1.4928202
Comments

Publisher version available from AIP at this link.

Rights Statement

© 2015 AIP Publishing LLC.

Citation Information
Ronald J Tackett, Jagdish Thakur, Nathaniel Mosher, Emily Perkins-Harbin, et al.. "A Method for Measuring the Néel Relaxation Time in a Frozen Ferrofluid" Journal of Applied Physics Vol. 118 Iss. 6 (2015) p. 064701 - 064701-5 ISSN: 0021-8979
Available at: http://works.bepress.com/ronald-tackett/6/