Nunley, Timothy Nathan Willett-Gies, Travis I. Cooke, Jacqueline A. Manciu, Felicia S. Marsik, Premysl Bernhard, Christian Zollner, Stefan 2016-08-04 Using spectroscopic ellipsometry, the authors determined the optical constants (complex dielectric function) for (LaAlO₃)_0.3(Sr₂AlTaO₆) _0.35 (LSAT) from 0.01 to 6.5 eV. Above 0.5 eV, the data were described with a sum of two Tauc-Lorentz oscillators and two poles. A direct gap of 5.8 ± 0.1 eV was found. An Urbach tail extends to even lower photon energies and makes the crystal opaque above 4.8 eV. Using Fourier-transform infrared ellipsometry, the lattice dynamics was studied. Nine pairs of transverse/longitudinal phonons were found and attributed to disorder in the La/Sr sublattice, ordering in the Al/Ta sublattice, and two- phonon absorption application/pdf https://folia.unifr.ch/global/documents/305252 https://folia.unifr.ch/documents/305252/files/ber_ocb.pdf eng info:eu-repo/semantics/altIdentifier/doi/10.1116/1.4960356 info:eu-repo/semantics/openAccess License undefined Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films. - 2016, vol. 34, no. 5, p. 051507 info:eu-repo/classification/udc/53 Optical constants, band gap, and infrared-active phonons of (LaAlO₃)_0.3(Sr₂AlTaO₆)_0.35 (LSAT) from spectroscopic ellipsometry http://purl.org/coar/resource_type/c_6501