Preparation and magnetoresistance of thin CrO2 films

Highly textured chromium dioxide (CrO2) films have been deposited on Al2O3 single-crystal substrates by atmospheric pressure chemical vapor deposition method (CVD). X-ray diffraction patterns show that the CrO2 films are (1 0 0)-oriented on Al2O3 (0 0 1) substrates, and are (1 0 1)-oriented on Al2O3 (0 1 2) substrates. Scanning electron microscopy images indicate that the (1 0 0)-oriented CrO2 films grown on Al2O3 (0 0 1) substrates have smoother surface and better qualities than that grown on Al2O3 (0 1 2) substrate. At room temperature, the magnetoresistance of the (1 0 0)- and (1 0 1)-oriented CrO2 films are nearly same, and both show a linear dependence on applied magnetic field. While at 80 K, the (1 0 1)-oriented CrO2 films show a much larger magnetoresistance compared with the (1 0 0)-oriented CrO2 films. The reasons are briefly discussed.