Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Advanced characterization of magnetization dynamics in iron oxide magnetic nanoparticle tracers



Thinh Bui, Adam Biacchi, Brianna Bosch Correa, Cindi L. Dennis, Weston L. Tew, Angela R. Hight Walker, Solomon I. Woods


Characterization of the magnetization dynamics of single-domain magnetic nanoparticles (MNPs) is important for magnetic particle imaging (MPI), magnetic resonance imaging (MRI), and emerging medical diagnostic/therapeutic technologies. Depending on particle size and temperature, nanoparticle magnetization relaxation time constants span from nanoseconds to seconds. In solution, relaxation occurs via coupled Brownian and Néel relaxation mechanisms. Even though their coexistence complicates analysis, the presence of two timescales presents opportunities for more direct control of magnetization behavior if the two processes can be understood, isolated, and tuned. Using high frequency coils and sample temperature tunability, we demonstrate unambiguous determination of the specific relaxation processes for iron oxide nanoparticles using both time and frequency domain techniques. Furthermore, we study the evolution of the fast dynamics at ≈ 10 nanosecond timescales, for magnetic field amplitudes relevant to MPI.
Applied Physics Letters


Bui, T. , Biacchi, A. , Correa, B. , Dennis, C. , Tew, W. , Hight Walker, A. and Woods, S. (2022), Advanced characterization of magnetization dynamics in iron oxide magnetic nanoparticle tracers, Applied Physics Letters, [online], (Accessed April 23, 2024)
Created January 5, 2022, Updated November 29, 2022