Control of magnetic properties in spinel ZnFe2O4 thin films through intrinsic defect manipulation

We present a systematic study of the magnetic properties of ZnFe 2O 4 thin films fabricated by pulsed laser deposition at low and high oxygen partial pressure and annealed in oxygen and argon atmosphere, respectively. The as-grown films show strong magnetization, closely related to a non-equilibrium distribution of defects, namely, Fe cations among tetrahedral and octahedral lattice sites. While the concentration of tetrahedral Fe cations declines after argon treatment at 250 degrees C, the magnetic response is enhanced by the formation of oxygen vacancies, evident by the increase in near-infrared absorption due to the Fe 2 +-Fe 3 + exchange. After annealing at temperatures above 300 degrees C, the weakened magnetic response is related to a decline in disorder with a partial recrystallization toward a less defective spinel configuration.