Longitudinal magnetoresistance of $CrO2$ thin films

The longitudinal magnetoresistance (LMR) of thin films of the putative half-metallic ferromagnet $CrO2$ deposited by chemical vapor deposition onto $TiO2/Si(111)$ substrates has been measured in the temperature range 0.55 K<T<4.2 K in magnetic fields up to 7 T. The dependence of the LMR on small changes in the angle between the applied field and the substrate plane was also measured at T=1.3 K. X-ray diffraction measurements showed that these films have a textured rutile structure with a axis and 〈110〉 orientations normal to the substrates. The LMR of these films at about 3 T was about twice that of similar films that showed only a 〈100〉 orientation normal to their $ZrO2$ substrates. A change in the substrate orientation relative to the applied field direction of 10° caused a 25% decrease in the magnitude of the LMR at 3 T. The results suggest that the existence of the 〈110〉 crystallite structure strongly affects the magnetoresistance.