Temperature dependence of ac response in diluted half-metallic CrO2 powder compact

We present a study on temperature dependence of impedance spectra of the cold-pressed chromium dioxide (CrO 2 )–titanic dioxide (TiO 2 ) composite over the temperature range of 77–300 K, and over the frequency range of 40 Hz–500 kHz. The microstructure of the sample is analyzed using transmission electron microscopy (TEM), SEM and X-ray diffraction (XRD). The impedance spectra exhibit a strong dependence upon temperature. By evaluating the ac electricity behavior of the composite, we find the experimental data are successfully described by a power-law behavior σ ac = A ( T ) ω s , in which the frequency exponent s shows slightly greater than a universal value (0≤ s ≤1), and rises approximately linearly with temperature over a broad range of low temperature.