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Evidence for Order Parameter Spatial Fluctuations in TlGa(Se 1− x S x ) 2 Crystals by Raman Spectroscopoy
Author(s) -
Burlakov V. M.,
Anikiev A. A.,
Yakheev M. R.
Publication year - 1990
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221610243
Subject(s) - raman spectroscopy , ferroelectricity , phonon , instability , condensed matter physics , crystal (programming language) , order (exchange) , line (geometry) , component (thermodynamics) , materials science , spectral line , physics , optics , quantum mechanics , mathematics , geometry , finance , computer science , dielectric , economics , programming language
Raman spectra of the ferroelectric layered crystals TIGa(Se 1− x S x ) 2 are studied for concentrations x = 0, 0.05, 0.15 over a wide temperature range. The contribution of the order parameter spatial fluctuations to the spectral line parameters is defined by comparing the concentration dependence of the low‐frequency integral intensity to that of the splitting of a doubly degenerated hard mode at ≈ 55 cm −1 . Large spatial fluctuations of the order parameter are assumed to be caused by the presence of an order–disorder component in the ferroelectric instability of the layered crystal. The order—disorder component is thought to be related to a narrow one‐dimensional soft phonon band.