The structure and magnetic properties of Mn–Zn ferrite thin films fabricated by alternately sputtering

Mn1−xZnxFe2O4 thin films with various Zn content were deposited on Si (1 0 0) substrate by alternately sputtering from two targets with the composition of MnFe2O4 and ZnFe2O4, respectively. The as-deposited films are amorphous. After being annealed in the vacuum furnace with air pressure PAir = 2 × 10−1 Pa at suitable temperature, crystalline Mn–Zn ferrite films are obtained. The optimum annealing temperature is 550 °C, at which a maximum of saturation magnetization and a minimum of coercivity are obtained. For Mn1−xZnxFe2O4 thin films, the saturation magnetization increases firstly then decreases and coercivity decreases monotonously with increasing Zn content. The Mn–Zn ferrite thin films with ZnFe2O4 underlayer exhibit better magnetic properties than those deposited directly on Si substrates because ZnFe2O4 underlayer not only can impede the diffusion between the substrate and magnetic layer, but also can decrease the strain caused by mismatch between the lattice constants of the substrate and thin films.