Room temperature ferrimagnetism and low temperature disorder effects in zinc ferrite thin films

• Zinc ferrite thin films were prepared by RF sputtering.
• The films were annealed at 400 °C and 600 °C.
• Grain growth was observed with annealing.
• The highest magnetization of 18 emu/cc was obtained for zinc ferrite film of thickness 120 nm.
• The films were ferrimagnetic at room temperature.

Zinc ferrite is a normal spinel and antiferromagnetic in nature with a Neel temperature of 10 K in the micron regime. It exhibits interesting features like superparamagnetism, spin glass and ferrimagnetism in the nano-regime. These anomalies make zinc ferrite striking among various other spinels. Further, in the thin film form, the magnetic properties are dependent on preparative techniques, annealing and deposition parameters. In the present work, zinc ferrite thin films were prepared by RF sputtering. The films were annealed at 400° C and 600° C. The thickness and composition of films were estimated by employing Rutherford Backscattering Spectrometry (RBS). The structural and microstructural studies conducted using Glancing X Ray Diffractometer (GXRD) and Transmission Electron Microscope (TEM) indicates the formation of a spinel phase and grain growth was observed with annealing. Magnetic measurements were carried out using a Superconducting Quantum Interferometer Device–Vibrating Sample Magnetometry (SQUID VSM). The films were found to be ferrimagnetic at room temperature and Field Cooling–Zero Field Cooling (FC–ZFC) studies indicate the presence of disorders.