Long-wavelength phonon dynamics in incommensurate Bi2Sr2CaCu2O(8+delta) crystals by Brillouin light scattering spectroscopy

Room temperature phonon dynamics in crystals of the high-Tc superconductor Bi2Sr2CaCu2O(8+delta) were probed using Brillouin light scattering spectroscopy. Eight distinct acoustic modes were observed and identified, including two quasi-longitudinal bulk modes and four quasi-transverse bulk modes. A...

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Bibliographic Details
Published in:arXiv.org 2022-02
Main Authors: McNiven, Bradley D E, LeBlanc, James P F, Andrews, Gordon T
Format: Article
Language:English
Subjects:
Crystals
Frequency shift
Light scattering
Phonons
Room temperature
Spectroscopy
Spectrum analysis
Online Access:Get full text
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Summary:Room temperature phonon dynamics in crystals of the high-Tc superconductor Bi2Sr2CaCu2O(8+delta) were probed using Brillouin light scattering spectroscopy. Eight distinct acoustic modes were observed and identified, including two quasi-longitudinal bulk modes and four quasi-transverse bulk modes. A peak at a frequency shift of ~95 GHz with behaviour reminiscent of an optic phonon was also observed in the spectra. The existence and nature of these modes is a manifestation of the incommensurate structure of Bi2Sr2CaCu2O(8+delta) and suggests that it may be categorized as a so-called composite incommensurate crystal comprised of two weakly interacting sublattices. A mass ratio of m1/m2=0.36 obtained from the two measured quasi-longitudinal acoustic velocities led to sublattice assignments of Bi2Sr2O4 and CaCu2O4. The Brillouin data also places an upper limit of ~10 GHz on the crossover frequency between commensurate and incommensurate phonon dynamics.
ISSN:2331-8422
DOI:10.48550/arxiv.2202.02577