High-coercivity Co-ferrite thin films on (100)-SiO2 substrate

Co-ferrite films were deposited on SiO2 single-crystal substrates. The as-deposited films were amorphous. The crystallization required an annealing at 700 °C or higher. Magnetic properties were found to be strongly dependent on annealing temperature, annealing duration, and film thickness. A small film thickness can restrict the formation of large particles. A coercivity as high as 9.3 kOe was achieved in the 50 nm film after annealing at 900 °C for 15 min deposited on (100)-SiO2 substrate. The high coercivity was associated with a nanostructure, lattice strain, and larger Raman shift with a relatively sharp peak.