ESR study of Co-doped TiO2 thin films

Co:TiO2 thin films prepared by reactive co-sputtering deposition were studied by electron spin resonance (ESR) technique. Magnetization measurements showed hysteretic behavior with the coercive field between 55 and 65 Oe and the saturation magnetization at room temperature ranging from 7 (2.2% Co) to 28 emu/cm(3) (8.5% Co). ESR measurements at X-band (9.5 GHz) revealed an anomaly in the temperature behavior of the absorption intensity near the temperature at 60 K. This behavior is attributed to an unconventional spin-glass-like behavior, which results from competition of long-range dipole-dipole interaction and anisotropy fields in ferromagnetic Co nanoparticles. (C) 2002 Elsevier Science B.V. All rights reserved.