Static Scaling on an Interacting Magnetic Nanoparticle System

The field dependence of the ac susceptibility of a concentrated frozen ferrofluid containing ultrafine Fe-C particles of monodisperse nature has been analyzed using static scaling. For the first time, a divergent behavior of the nonlinear susceptibility of a dipole-dipole interacting system is demonstrated. From the analysis, the critical exponents $\gamma =4.0\mathrm{}\pm 0.2$ and $\beta =1.2\mathrm{}\pm 0.1$ were extracted. The results support the existence of a low temperature spin-glass-like phase in interacting magnetic nanoparticle systems.