Negative magnetoresistance in reactive sputtered non-uniform amorphous FexTi1−xOδ films

Non-uniform amorphous FexTi1−xOδ films were fabricated by reactive sputtering. Fe0, Fe2+, Fe3+, Ti3+, Ti4+ and O2− ions are detected in the form of non-uniform distribution. The films are semiconducting. Below 50 K, the resistivity significantly increases with decreasing temperature, satisfying the variable-range hopping conductance. Magnetoresistance (MR) largely increases with the decrease of temperature below 50 K. At x = 0.52, MR is −8% at 300 K and −32% at 3 K. The large low-temperature MR is related to the antiferromagnetic disordered moments.