Ferromagnetism in Fe and Co‐implanted SnO ₂ films

Abstract

Using the ion implantation technique SnO2 thin films sputtered onto glass and fused silica substrates were doped with various concentrations of Fe and Co. The films have been characterized by optical transmission, ellipticity, and susceptibility measurements. The optical data reveal a fundamental optical gap of 3.5 eV and a refractive index of 2.0 to 2.1. While the optical properties vary very little with the substrate, the annealing and the type of dopant, the susceptibility shows striking variations. Thus, the unannealed films deposited onto glass display at 10 K much larger magnetic moments than films on fused silica. While the former films loose rapidly their magnetization with increasing temperature, the latter keep about 70% still at room-temperature. Various models are discussed to account for the observed variations with substrate, temperature, and annealing. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)