Enhanced magnetoresistance in half-metallic CrO2–TiO2 composites

CrO2–TiO2 composites were synthesized by a high temperature and high pressure method (HTHP). The CrO2–TiO2 composites are composed of large rod-like CrO2 crystals separated by TiO2 nanoparticles. The saturation magnetization of the CrO2 in the composites is very close to the theoretical value. The CrO2–TiO2 composites show greatly enhanced magnetoresistance than that of pure CrO2. This is mainly attributed to spin-dependent tunneling between adjacent CrO2 grains enhanced by the addition of TiO2. The tunneling mechanism in the composites can be best described by the fluctuation-induced tunneling model as convinced by the temperature dependence of the conductivity of the CrO2–TiO2 composites at low temperature. - Highlights: ► CrO2–TiO2 composites consist of large rod-like CrO2 crystals and TiO2 nanoparticles. ► The composites show enhanced magnetoresistance than that of pure CrO2. ► TiO2 in composites acts as grain boundary barrier for spin-dependent tunneling. ► The tunneling mechanism is best described by fluctuation-induced tunneling model