Structural and Magnetic Features of $Mn_{1-x}Zn_xFe_2O_4$ Nanoparticles

This paper reports on the magnetic properties of $Mn_{1-x}Zn_x$-ferrite nanoparticles. Different x compositions of the magnetic material have been considered. Field- and temperature-dependent magnetization curves and electron paramagnetic resonance (EPR) at different temperatures were used to reveal the magnetic properties of the samples. For x=0.5, the EPR spectra consist of a single resonance signal, strongly symmetrical, with g = 3.25 close to 2073 G, and an asymmetric line corresponding to g = 4.4 for x = 0. The asymmetry is attributed to a random distribution of the anisotropy in the system, with perpendicular and parallel modes, giving information about the effective anisotropy of the system. For high concentrations, the resonant field shifts to 2875 G. Magnetization measurements as function of temperature at 60 Oe according to the standard zero field cooling (ZFC) and field cooling (FC) procedures are reported. The behavior of field cooling magnetization (MFC) at low temperatures evidences the presence of strong interparticles interactions.