Regarding The Neel Relaxation Time Constant In Magnetorelaxometry

Magnetorelaxometry (MRX) is a sensitive measurement technique frequently employed in biomedical applications for imaging magnetic nanoparticles (MNP). In this article, we employ a first principles model to investigate the effects of different iron oxide MNP sample properties on the Neel relaxation time constant tau(N) in magnetorelaxometry. Using this model, we determined that dipolar interactions start to have an impact on the MRX signal from Fe concentrations of 100 mmol/l and result in a smaller tau(N). Additionally, the micromagnetic damping constant, closely related to tau(N), was found to be between 0.0005 and 0.002 by comparison to an MRX measurement of iron oxide particles. This is significantly lower compared to the bulk value of 0.07 for this material. (C) 2014 AIP Publishing LLC.