Magnetic glassy phase in Zn0.85Fe0.15O diluted magnetic semiconducting nanoparticles

The authors have investigated the ground state magnetic phase and the optical band gap of chemically synthesized Zn0.85Fe0.15O diluted magnetic semiconducting nanoparticles (similar to 7.5 nm). The temperature dependent magnetization study shows strong irreversibility along with a cusplike anomaly, which is ascribed to a freezing to a cluster glasslike magnetic ground state. This assignment is further established by Arrott-Belov-Kouvel plots along with S-like nonsaturating magnetization versus field curves. The finite size ferromagnetic clusters which are formed due to an enhanced grain surface effect in the system undergo random dipolar intercluster interactions, giving rise to strong competitive ferromagnetic and antiferromagnetic interactions, finally leading to the freezing of those clusters.