Dynamic hysteresis loops of iron oxide nanoflowers

Iron oxide nanoparticles have many potential applications in biomedicine, including magnetic hyperthermia and magnetic particle imaging. These applications depend sensitively on the magnetization (M) of the particles under a rapidly oscillating applied field H. The internal structure of nanoparticles strongly affects the magnetic behavior. Iron oxide nanoflowers, particles composed of several small crystallites fused together with an irregular surface, are promising for magnetic hyperthermia due to their large loss power [1]. We present dynamic measurements of M(H) at 230 kHz for iron oxide nanoflowers. The nanoflowers were synthesized by a polyol method described previously [2]. The cores are 22 ± 9 nm and are coated in dextran (synomag^®-D). The particles are suspended in H₂O at 14.2 mg(Fe)/mL. The resulting M(H) curves show linear behavior (open ellipsoidal loops) at low fields, transitioning to nonlinear behavior at a field of 6 kA/m. These results show directly the magnetic reversal behavior of iron oxide nanoflowers in the linear and nonlinear regimes, and will help guide applications of these particles.

References:

[1] P. Bender et al, The Journal of Physical Chemistry C 122, 2068 (2018)

[2] H. Gavilan et al, Particle & Particle Systems Characterization, 1700094 (2017)