Relationship between blocking temperature and strength of interparticle interaction in magnetic nanoparticle systems

Mohindar S. Seehra; Kelly L. Pisane

paper

Relationship between blocking temperature and strength of interparticle interaction in magnetic nanoparticle systems

arXiv:1510.08366

Abstract

In magnetic nanoparticle systems, the variation of the blocking temperature $T_{B}$ with the measuring frequency $f_{m}$ is often used to determine the strength of the interparticle interactions (IPI) through a parameter $Φ$ or the Vogel-Fulcher temperature $T_{o}$ . Presence of IPI is inferred if $T_{o}$ $>$ 0 and $Φ =$ $Δ$ $T_{B}$ $/$ $[T_{B} Δ$ $l o g_{10}$ $f_{m}] <$ 0.13 where $Δ$ signifies changes in $T_{B}$ and $f_{m}$ . Here it is shown that these two parameters are related by the Eq. $Φ =$ $Φ_{o}$ $\approx$ 0.11 to 0.15 is a constant of the system depending on the magnitudes of measuring frequency and $Φ =$ $Φ_{o}$ $[1 - T_{o} / T_{B}]$ where the attempt frequency $f_{o}$ of the Néel relaxation. Experimental verification of this relationship is also presented using data on a variety of nanoparticle systems.