Two-mode behavior of the PbMg1/3Nb2/3O3 relaxor

Vakhrushev, S. B.; Burkovsky, R. G.; Shapiro, S. M.; Ivanov, Alexander S.

doi:10.1134/s106378341005001x

Cited by 17 publications

(16 citation statements)

References 16 publications

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“…The further point of discussion is the behaviour found recently by Vakhrushev et al [137]. They measured the scattering at the (2, 0, 0) and (3, 0, 0) Bragg reflections and the results and the corresponding single optic mode fit is shown at a temperature of 1050 K in Figure 26.…”

Section: Phonon Dynamics In Pmnmentioning

confidence: 92%

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Relaxing with relaxors: a review of relaxor ferroelectrics

Cowley

Gvasaliya

Lushnikov

et al. 2011

Advances in Physics

424

313

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Section: Phonon Dynamics In Pmnmentioning

confidence: 92%

“…[135] and the stars Ref. [137]. Open squares were obtained from the data taken around the (2,2,0) Bragg peak and the stars were obtained from the data near the (0, 0, 3) Bragg peak, and all the other data were taken near the (0, 0, 2) Bragg peak.…”

Section: Phonons and The Waterfall Effectmentioning

confidence: 99%

Relaxing with relaxors: a review of relaxor ferroelectrics

Cowley

Gvasaliya

Lushnikov

et al. 2011

Advances in Physics

424

313

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“…All INS data are for the underdamped modes. INS [8,9] INS [6] INS [3] model (ii) model (iv) HRS [17] Raman [3] Raman [13] …”

Section: Fig 15mentioning

confidence: 99%

Infrared, terahertz, and microwave spectroscopy of the soft and central modes in Pb(Mg1/3Nb2/
Nuzhnyy
¹
,
Petzelt
²
,
Bovtun
³

et al. 2017
Phys. Rev. B
21
1
6
0
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From the new infrared (IR) reflectivity and time-domain terahertz (THz) spectra combined with available high-frequency dielectric data above the MHz range in a broad temperature range of 10-900 K, a full picture of the soft and central mode behavior in the classical relaxor ferroelectric Pb(Mg 1/3 Nb 2/3 )O 3 (PMN) is suggested. A detailed comparison is given with the recent hyperRaman spectroscopy data (Hehlen et al. Phys. Rev. Lett. 117, 155501 (2016)), and also with other available experiments based on inelastic light and neutron scattering. It is revealed that each type of experiment provides slightly different data. The closest agreement is with the hyper-Raman data, both techniques yield the same number of soft-mode components and the same hightemperature softening towards the temperature T* ≈ 400 K. In addition to evaluation of the IRTHz data using fitting with standard factorized form of the dielectric function, we performed a successful fitting of the same data using the effective medium approach (EMA), originally based on the assumption that the mesoscopic structure of PMN consists of randomly oriented uniaxially anisotropic polar nanodomains (PNDs) with somewhat harder TO polar modes in the direction along the local PND dipole (Phys. Rev. Lett. 96, 027601 (2006)). Evaluation using the Bruggeman EMA modelling has been successfully applied in the entire investigated temperature range. These results suggest that the response perpendicular to the local dipole moment, at high temperatures induced by random fields rather than PNDs, undergoes a classical softening from high temperatures with permittivity obeying the Curie-Weiss law, ε  = C/(T-T C ), C = 1.7 x 10 5 K and T C = 380 K, whereas the response parallel to it shows no softening. Below the Burns temperature ~620 K, a GHz relaxation ascribed to flipping of the PNDs emerges from the soft mode response, slows down and broadens, remaining quite strong towards the cryogenic temperatures, where it can be assigned to fluctuations of the PND boundaries.

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“…Many spectroscopic experiments have been performed in an attempt to relate these assumptions to the dynamical phenomena. These investigations include neutron scattering [35][36][37][38][39], Raman scattering [40], and infrared absorption [41] experiments. Another technique, hyper-Raman scattering (HRS) [42], is particularly suitable for probing the low-frequency polar modes in nonpolar crystal phases [43,44].…”

mentioning

confidence: 99%

“…However, these findings raised new questions, such as the following: Are there one or two soft modes well above T d , when the material is in its paraelectric state [35,39]? How do these excitations relate to the vibrations observed below T f [40,41,49]?…”

mentioning

confidence: 99%

Relaxor Ferroelectrics: Back to the Single-Soft-Mode Picture

et al. 2016

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The fluctuations of electric polarization in a disordered ferroelectric substance, relaxor crystal PbMg_{1/3}Nb_{2/3}O_{3} (PMN), were studied using a nonlinear inelastic light-scattering technique, hyper-Raman scattering, within a 5-100 cm^{-1} spectral interval and in a broad temperature range from 20 to 900 K. The split ferroelectric mode reveals a local anisotropy of up to about 400 K. Spectral anomalies observed at higher temperatures are explained as due to avoided crossing of the single primary polar soft mode with a temperature-independent, nonpolar spectral feature near 45 cm^{-1}, known from Raman scattering. The temperature changes of the vibrational modes involved in the measured fluctuation spectra of PMN were captured in a simple model that accounts for the temperature dependence of the dielectric permittivity as well. The observed slowing down of the relaxational dynamics directly correlates with the huge increase of the dielectric permittivity.

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Two-mode behavior of the PbMg1/3Nb2/3O3 relaxor

Cited by 17 publications

References 16 publications

Relaxing with relaxors: a review of relaxor ferroelectrics

Relaxing with relaxors: a review of relaxor ferroelectrics

Infrared, terahertz, and microwave spectroscopy of the soft and central modes in Pb(Mg1/3Nb2/
Nuzhnyy
¹
,
Petzelt
²
,
Bovtun
³

et al. 2017
Phys. Rev. B
21
1
6
0
View full text Add to dashboard Cite

Relaxor Ferroelectrics: Back to the Single-Soft-Mode Picture

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Two-mode behavior of the PbMg1/3Nb2/3O3 relaxor

Cited by 17 publications

References 16 publications

Relaxing with relaxors: a review of relaxor ferroelectrics

Relaxing with relaxors: a review of relaxor ferroelectrics

Infrared, terahertz, and microwave spectroscopy of the soft and central modes in Pb(Mg1/3Nb2/Nuzhnyy1, Petzelt2, Bovtun3 et al. 2017Phys. Rev. B21160View full textAdd to dashboardCite

Relaxor Ferroelectrics: Back to the Single-Soft-Mode Picture

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Infrared, terahertz, and microwave spectroscopy of the soft and central modes in Pb(Mg1/3Nb2/
Nuzhnyy
¹
,
Petzelt
²
,
Bovtun
³

et al. 2017
Phys. Rev. B
21
1
6
0
View full text Add to dashboard Cite