Non-c-asis-oriented EuBa2Cu3O7-delta thin films grown on Al2O3(1102) substrates with CeO2 buffer layers

EuBa2Cu3O7-delta (EBCO) thin films with different growth orientations were prepared on Al2O3(1 (1) over bar 02) substrates with CeO2 buffer layers by dc magnetron sputtering. The EBCO thin films were deposited immediately aft er off-axis rf magnetron sputtering of CeO2(001) films. The effects of subs trate temperature and oxygen concent on epitaxial orientation of EBCO thin films were examined. With the increase in oxygen concentration, the surface roughness of an EBCO thin film increased. An appropriate oxygen concentrat ion existed. It was clarified that the orientation of an EBCO thin film dep ended on CeO2 film thickness. The (100)- and (110)-oriented EBCO thin films were obtained on CeO2 buffer layers 30-90 Angstrom thick and more than 700 Angstrom thick, respectively. The (100)- and (110)-oriented EBCO films had in-plane epitaxial orientation relationships of Al2O3[11 (2) over bar 0] \ \ CeO2[100] \\ EBCO[013] and Al2O3[11 (2) over bar 0] \\ CeO2[100] \\ EBCO[ 110], respectively. The (100)-oriented EBCO films deposited on 50-Angstrom- thick CeO2 (001) buffer layers had T-ce's of 72.0 K, and (110)-oriented EBC O films deposited on 750-Angstrom-thick CeO2(001) buffer layers had T-ce's of 70.0 K. The T-ce decreased with increasing CeO2 buffer layer thickness a bove 800 Angstrom. The a-axis-oriented EBCO thin films exhibited T-ce's of about 85.4 K on the 50-Angstrom-thick CeO2 buffer layers prepared by a self -template method.