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 degrees 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. (C) 1999 American Institute of Physics. [S0003-6951(99)02203-2].