Brillouin zone center phonon modes in ZnGa2O4
Abstract
Infrared-active lattice mode properties of melt-grown high-quality single bulk crystals of ZnGa2O4 are investigated by combined spectroscopic ellipsometry and density functional theory computation analysis. The normal spinel structure crystals are measured by spectroscopic ellipsometry at room temperature in the range of 100 cm–1–1200 cm–1. The complex-valued dielectric function is determined from a wavenumber-by-wavenumber approach, which is then analyzed by the four-parameter semi-quantum model dielectric function approach augmented by impurity mode contributions. We determine four infrared-active transverse and longitudinal optical mode pairs, five localized impurity mode pairs, and the high frequency dielectric constant. All four infrared-active transverse and longitudinal optical mode pairs are in excellent agreement with results from our density functional theory computations. With the Lyddane–Sachs–Teller relationship, we determine the static dielectric constant, which agrees well with electrical capacitance measurements performed on similarly grown samples. We also provide calculated parameters for all Raman-active and for all silent modes and, thereby, provide a complete set of all symmetry predicted Brillouin zone center modes.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Aug 03, 2020
- Source ID
- 10.1063/5.0012526
Entities
People
- K. Irmscher
- Mathias Schubert
- Matthew Hilfiker
- Megan Stokey
- Rafał Korlacki
- Sean Knight
- Vanya Darakchieva
- Zbigniew Galazka
Organizations
- Air Force Office of Scientific Research
- Leibniz Institute for Crystal Growth
- Linköping University
- National Science Foundation
- Swedish Foundation for Strategic Research
- Swedish Governmental Agency for Innovation Systems
- Swedish Research Council
- University of Nebraska–Lincoln