Lattice dynamics of orthorhombic NdGaO₃

Authors

Alyssa MockFollow
Rafal Korlacki, University of Nebraska-LincolnFollow
Sean Knight, University of Nebraska-LincolnFollow
Megan Stokey, University of Nebraska-LincolnFollow
A. Fritz, University of Nebraska-Lincoln
Vanya Darakchieva, Linköping University, SwedenFollow
Mathias Schubert, University of Nebraska - LincolnFollow

Date of this Version

5-17-2019

Citation

A. MOCK et al. PHYSICAL REVIEW B 99, 184302 (2019).

DOI: 10.1103/PhysRevB.99.184302

Comments

©2019 American Physical Society. Used by permission.

Abstract

A complete set of infrared-active and Raman-active lattice modes is obtained from density functional theory calculations for single-crystalline centrosymmetric orthorhombic neodymium gallate. The results for infraredactive modes are compared with an analysis of the anisotropic long-wavelength properties using generalized spectroscopic ellipsometry. The frequency-dependent dielectric function tensor and dielectric loss function tensor of orthorhombic neodymium gallium oxide are reported in the spectral range of 80–1200 cm⁻¹. A combined eigendielectric displacement vector summation and dielectric displacement loss vector summation approach augmented by considerations of lattice anharmonicity is utilized to describe the experimentally determined tensor elements. All infrared-active transverse and longitudinal optical mode pairs obtained from density functional theory calculations are identified by our generalized spectroscopic ellipsometry investigation. The results for Raman-active modes are compared to previously published experimental observations. Static and high-frequency dielectric constants from theory as well as experiment are presented and discussed in comparison with values reported previously in the literature.