Acoustic anomaly and the Landau free energy of incommensurate K2SeO4

Gen Li; N. Tao; Le Van Hong; H. Z. Cummins; C. Dreyfus; M. Hebbache; R. M. Pick; J. Vagner

doi:10.1103/PhysRevB.42.4406

Acoustic anomaly and the Landau free energy of incommensurate K2SeO4

Gen Li, N. Tao, Le Van Hong, H. Z. Cummins, C. Dreyfus, M. Hebbache, R. M. Pick, J. Vagner

Research output: Contribution to journal › Article › peer-review

27 Scopus citations

Abstract

Brillouin-scattering studies of the longitudinal-acoustic mode propagating along the c* axis of K2SeO4 were performed in the vicinity of the incommensurate phase transition in both 90°and 180°scattering geometries. A theoretical derivation of the complex elastic constant C33() was carried out within the mean-field approximation including both bilinear (Landau-Khalatnikov) coupling to the amplitude mode, and anharmonic fluctuation contributions from the 2 soft mode above TI and from pairs of amplitude modes and phase modes below TI. Comparison between theory and the Brillouin data led to an excellent fit using free-energy parameters close to values deduced from previous static and dynamical experiments. Our measurements also indicate that the phason gap (0) is at least 100 GHz.

Original language	English (US)
Pages (from-to)	4406-4425
Number of pages	20
Journal	Physical Review B
Volume	42
Issue number	7
DOIs	https://doi.org/10.1103/PhysRevB.42.4406
State	Published - 1990
Externally published	Yes

ASJC Scopus subject areas

Condensed Matter Physics

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10.1103/PhysRevB.42.4406

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title = "Acoustic anomaly and the Landau free energy of incommensurate K2SeO4",

abstract = "Brillouin-scattering studies of the longitudinal-acoustic mode propagating along the c* axis of K2SeO4 were performed in the vicinity of the incommensurate phase transition in both 90°and 180°scattering geometries. A theoretical derivation of the complex elastic constant C33() was carried out within the mean-field approximation including both bilinear (Landau-Khalatnikov) coupling to the amplitude mode, and anharmonic fluctuation contributions from the 2 soft mode above TI and from pairs of amplitude modes and phase modes below TI. Comparison between theory and the Brillouin data led to an excellent fit using free-energy parameters close to values deduced from previous static and dynamical experiments. Our measurements also indicate that the phason gap (0) is at least 100 GHz.",

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T1 - Acoustic anomaly and the Landau free energy of incommensurate K2SeO4

AU - Li, Gen

AU - Tao, N.

AU - Hong, Le Van

AU - Cummins, H. Z.

AU - Dreyfus, C.

AU - Hebbache, M.

AU - Pick, R. M.

AU - Vagner, J.

PY - 1990

Y1 - 1990

N2 - Brillouin-scattering studies of the longitudinal-acoustic mode propagating along the c* axis of K2SeO4 were performed in the vicinity of the incommensurate phase transition in both 90°and 180°scattering geometries. A theoretical derivation of the complex elastic constant C33() was carried out within the mean-field approximation including both bilinear (Landau-Khalatnikov) coupling to the amplitude mode, and anharmonic fluctuation contributions from the 2 soft mode above TI and from pairs of amplitude modes and phase modes below TI. Comparison between theory and the Brillouin data led to an excellent fit using free-energy parameters close to values deduced from previous static and dynamical experiments. Our measurements also indicate that the phason gap (0) is at least 100 GHz.

AB - Brillouin-scattering studies of the longitudinal-acoustic mode propagating along the c* axis of K2SeO4 were performed in the vicinity of the incommensurate phase transition in both 90°and 180°scattering geometries. A theoretical derivation of the complex elastic constant C33() was carried out within the mean-field approximation including both bilinear (Landau-Khalatnikov) coupling to the amplitude mode, and anharmonic fluctuation contributions from the 2 soft mode above TI and from pairs of amplitude modes and phase modes below TI. Comparison between theory and the Brillouin data led to an excellent fit using free-energy parameters close to values deduced from previous static and dynamical experiments. Our measurements also indicate that the phason gap (0) is at least 100 GHz.

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Acoustic anomaly and the Landau free energy of incommensurate K2SeO4

Abstract

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