Effects of Substrate Temperature, Oxygen Pressure and Laser Fluence on Structural and Magnetic Properties of Pulsed Laser-Deposited Cobalt Ferrite Thin Films

Abstract

Cobalt ferrite (CFO) thin films were grown on fused quartz substrate using pulsed laser deposition technique. The effects of various process parameters viz. substrate temperature, oxygen pressure, and laser energy fluence on structural, morphological, and magnetic properties were studied using X-ray diffraction (XRD), atomic force microscope (AFM), and vibrating sample magnetometer (VSM), respectively. The film deposited at the lower substrate temperature of 400 °C showed growth of CFO along preferred [110] direction and becomes textured for the substrate temperature of 800 °C with increase in grain size from 21 to 46 nm measured using AFM. The value of saturation magnetization (4 πMs) increases from 1940 to 2460 G with increase in substrate temperature from 400 to 800 °C, respectively. The CFO thin film deposited at 400 °C showed a coercivity value of 1880 Oe, which decreased to 670 Oe for 800 °C. The 4 πMs values first decrease with increase in oxygen pressure up to 0.4 mbar then increased for higher oxygen pressures. The H c value increases from 670 to 1290 Oe when oxygen pressure is increased from 0.2 to 0.4 mbar, which finally decreased to 1100 Oe for an oxygen pressure of 0.8 mbar. The structural and magnetic properties of CFO thin films are also observed to be influenced greatly by laser energy fluence. The varied magnetic properties of CFO thin films at different deposition conditions in pulsed laser deposition are interesting and may be useful for possible applications.