TY - JOUR
T1 - Anisotropy and phonon modes from analysis of the dielectric function tensor and the inverse dielectric function tensor of monoclinic yttrium orthosilicate
AU - Mock, A.
AU - Korlacki, R.
AU - Knight, S.
AU - Schubert, M.
N1 - Funding Information:
The authors thank Larry Alegria (Scientific Materials Corp.) for detailed information on the samples. This work was supported in part by the National Science Foundation (NSF) through the Center for Nanohybrid Functional Materials (EPS-1004094), the Nebraska Materials Research Science and Engineering Center (MRSEC) (DMR-1420645), and awards CMMI 1337856 and EAR 1521428. The authors further acknowledge financial support by the University of Nebraska-Lincoln, the J. A. Woollam Co., Inc., and the J. A. Woollam Foundation. The DFT calculations were performed using the computing resources of the Holland Computing Center and the Center for Nanohybrid Functional Materials at the University of Nebraska-Lincoln.
Publisher Copyright:
© 2018 American Physical Society.
PY - 2018/4/17
Y1 - 2018/4/17
N2 - We determine the frequency dependence of the four independent Cartesian tensor elements of the dielectric function for monoclinic symmetry Y2SiO5 using generalized spectroscopic ellipsometry from 40-1200 cm-1. Three different crystal cuts, each perpendicular to a principle axis, are investigated. We apply our recently described augmentation of lattice anharmonicity onto the eigendielectric displacement vector summation approach [A. Mock, Phys. Rev. B 95, 165202 (2017)2469-995010.1103/PhysRevB.95.165202], and we present and demonstrate the application of an eigendielectric displacement loss vector summation approach with anharmonic broadening. We obtain an excellent match between all measured and model-calculated dielectric function tensor elements and all dielectric loss function tensor elements. We obtain 23 Au and 22 Bu symmetry long-wavelength active transverse and longitudinal optical mode parameters including their eigenvector orientation within the monoclinic lattice. We perform density functional theory calculations and obtain 23 Au symmetry and 22 Bu transverse and longitudinal optical mode parameters and their orientation within the monoclinic lattice. We compare our results from ellipsometry and density functional theory and find excellent agreement. We also determine the static and above reststrahlen spectral range dielectric tensor values and find a recently derived generalization of the Lyddane-Sachs-Teller relation for polar phonons in monoclinic symmetry materials satisfied [M. Schubert, Phys Rev. Lett. 117, 215502 (2016)PRLTAO0031-900710.1103/PhysRevLett.117.215502].
AB - We determine the frequency dependence of the four independent Cartesian tensor elements of the dielectric function for monoclinic symmetry Y2SiO5 using generalized spectroscopic ellipsometry from 40-1200 cm-1. Three different crystal cuts, each perpendicular to a principle axis, are investigated. We apply our recently described augmentation of lattice anharmonicity onto the eigendielectric displacement vector summation approach [A. Mock, Phys. Rev. B 95, 165202 (2017)2469-995010.1103/PhysRevB.95.165202], and we present and demonstrate the application of an eigendielectric displacement loss vector summation approach with anharmonic broadening. We obtain an excellent match between all measured and model-calculated dielectric function tensor elements and all dielectric loss function tensor elements. We obtain 23 Au and 22 Bu symmetry long-wavelength active transverse and longitudinal optical mode parameters including their eigenvector orientation within the monoclinic lattice. We perform density functional theory calculations and obtain 23 Au symmetry and 22 Bu transverse and longitudinal optical mode parameters and their orientation within the monoclinic lattice. We compare our results from ellipsometry and density functional theory and find excellent agreement. We also determine the static and above reststrahlen spectral range dielectric tensor values and find a recently derived generalization of the Lyddane-Sachs-Teller relation for polar phonons in monoclinic symmetry materials satisfied [M. Schubert, Phys Rev. Lett. 117, 215502 (2016)PRLTAO0031-900710.1103/PhysRevLett.117.215502].
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U2 - 10.1103/PhysRevB.97.165203
DO - 10.1103/PhysRevB.97.165203
M3 - Article
AN - SCOPUS:85045959936
SN - 2469-9950
VL - 97
JO - Physical Review B-Condensed Matter
JF - Physical Review B-Condensed Matter
IS - 16
M1 - 165203
ER -