Reflectivity anisotropy of superconducting YBa2Cu3O7−x single crystals in the a-b plane

Abstract Polarized reflectivity spectra of orthorhombic and tetragonal YBa 2 Cu 3 O 7− x crystals in the 1–3 eV range were studied. Two types of anisotropy of optical properties (reflection) in the a - b plane were observed for superconducting orthorhombic crystals. The first is attributable to the crystal symmetry and reflects the nonequivalence of the a and b axes. The other type of anisotropy appears in the twinned regions of the crystal and is governed by the twin symmetry.