Magnetotransport study of granular chromium dioxide thin films prepared by the chemical vapor deposition technique

Abstract The temperature-dependent magnetotransport properties of granular chromium dioxide (CrO2) films with grain size about 1 μm grown by chemical vapor deposition on Si(0 0 1) substrates has been studied over a temperature range from 2 to 300 K. The magnetoresistance (MR) of about 20% at T=2 K decreases very fast with increasing temperature as a result of the rapid increase of the spin-independent hopping channel, whilst the temperature-dependent MR is almost the same for samples after 100 days annealing in air at room temperature, and its electrical resistivity at room temperature increases from roughly 50 to >75 μΩ m. The contribution to the conductance at T 6 K K is the second order inelastic hopping, which is amenable to σ∼T1.33. It becomes a poor metal at temperatures >160 K and its resistance follows R∼T 2 exp (−Δ/T) . We have shown experimentally that the room temperature annealing results in the decomposition of CrO2 into Cr2O3 mainly near the surface of the films.