Lattice Dynamics of Orthorhombic NdGaO₃

Authors

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

Document Type

Article

Date of this Version

2019

Citation

Physical Review B 99, 184302 (2019)

DOI: 10.1103/PhysRevB.99.184302

Comments

Copyright 2019 by the American Physical Society

https://doi.org/10.1103/PhysRevB.99.184302

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 infrared-active 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.