Infrared and far infrared reflection spectra of PrBa₂Cu₃O_6.3 films at different incident angles

The far infrared and infrared spectra of PrBa₂Cu₃O_6.3 films at incident angles of 7°, and 12°, and 30° were experimentally studied with the results presented here. The results show that (1) the films with Y-ZrO₂ substrate have c-axis orientation, which is perpendicular to the film plane; (2) in the spectra at the incident angle of 7° and 12°, six reflection peaks located at 110, 168, 240, 350, 570, and 635cm^-1 are observed respectively, which arise from six E_u modes vibrating parallel to the a-b plane; (3) as the incident angle rises to 30°, an additional mode at 465cm^-1 corresponding to an A_2u mode vibrating parallel to the c-axis appears. Besides, the influence of substrate on the reflectivity was also considered by comparing the spectra of films with different thickness.