Strain effects in thin films of CrO2 on rutile and sapphire substrates

Detailed x-ray diffraction characterizations were made of chromium dioxide films fabricated by chemical vapor deposition onto (100) and (110) oriented TiO2 and (0001) Al2O3 substrates. Pole figures were used to examine the epitaxy of these systems, and the lattice parameters were calculated using x-ray area maps. The film on (100) TiO2 exhibits the best epitaxy of the three; however, it is significantly strained relative to bulk CrO2. The film on (110) TiO2 is distorted from the ideal tetragonal structure by 0.17 degrees in the angle between the a and b lattice directions, and also exhibits significant mosaicity. The film on sapphire contains crystallites that have grown in three in-plane orientations, but exhibit the best rocking curve widths and the least degree of strain of the films studied. Magnetization and magnetotransport measurements are shown to demonstrate effects of strain and crystalline structure on the physical properties of these films. (C) 2001 American Institute of Physics.