Lifshitz points in uniaxial ferroelectrics

Folk, R.; Moser, G.

doi:10.1103/physrevb.47.13992

Cited by 40 publications

(44 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The experimental data for Sn 2 P 2 S 6 concerning the anomalous behavior of dielectric susceptibility [25], sound velocities [26], birefringence [27], diffuse scattering of X-rays [28] are generally well described in accordance with the predictions in [24] for the dipole Lifshitz point which is close to the tricritical point: the merging of these points preconditions a new universality class -the dipole tricritical Lifshitz point. However, the renormalization group description [24] is based on the uniaxial ferroelectric model of orthorhombic syngony -for this case the modulation wave in its IC phase is exactly transversal. Thus, there arises a great interest in the order parameter fluctuation spectrum in the vicinity of LP for the uniaxial ferroelectrics with the polarization and modulation wave vector in the monoclinic symmetry plane.…”

Section: Introductionsupporting

confidence: 60%

“…In [24] there has been pointed out the presence of a new universality class for the critical behavior of the uniaxial ferroelectrics in the vicinity of the Lifshitz point (LP) and in the vicinity of the tricritical Lifshitz point. The experimental data for Sn 2 P 2 S 6 concerning the anomalous behavior of dielectric susceptibility [25], sound velocities [26], birefringence [27], diffuse scattering of X-rays [28] are generally well described in accordance with the predictions in [24] for the dipole Lifshitz point which is close to the tricritical point: the merging of these points preconditions a new universality class -the dipole tricritical Lifshitz point.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Lattice dynamics and phase transitions in Sn_{2}P_{2}S(Se)_{6} ferroelectric crystals

Yevych¹,

Vysochanskii²

2006

Condens. Matter Phys.

View full text Add to dashboard Cite

Polarizable ion model was used in describing the lattice dynamics in the Sn 2 P 2 S 6 and Sn 2 P 2 Se 6 ferroelectric crystals and their solid solutions. There has been obtained a good agreement of the calculated phonon spectra with the experimental data of Raman and Brillouin spectroscopies, neutron scattering and ultrasound experiments. Paraelectric phase instability has been modelled by negative charge transferring from the tin cations to the chalcogen ions, and by increasing the polarizabilities of the latter. The ferroelectric phase has been stabilized by tin atom displacement from centrosymmetric positions and a partial reversal recharging between tin and chalcogen ions. The effective charges decreasing by moving from Sn 2 P 2 S 6 to Sn 2 P 2 Se 6 compounds determine the shift of condensation wave vector of soft optic phonons in paraelectric phase from q = 0 in sulfur compound to q > 0 in selenium compound. Such a change of dynamical instability character is connected with the appearance of incommensurate phase in Sn 2 P 2 (SexS 1−x ) 6 solid solution under x > 0.28. The "two-mode" instability emerged as possible in the vicinity of Lifshitz point -there have been modelled the condensation of soft optic mode with q ≈ 0 and mixed optic and transversal acoustic phonons near q > 0. This fact requires further experimental and theoretical investigations.

show abstract

Section: Introductionsupporting

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Lattice dynamics and phase transitions in Sn_{2}P_{2}S(Se)_{6} ferroelectric crystals

Yevych¹,

Vysochanskii²

2006

Condens. Matter Phys.

View full text Add to dashboard Cite

show abstract

“…3) was substantially lower than the mean-field Moreover, by far the best fit [see Fig. 3(a)] was obtained for adjustment to the expected logarithm-corrected power law 22,56,57 …”

Section: E Critical Behavior Of the Order Parametermentioning

confidence: 99%

“…1) at x ≈ 0.28 and T ≈ 280 K. Theoretically, the modulation period should diverge there. [22][23][24] Later, it was predicted that a similar LP could also occur in the temperature-pressure (T -p) phase diagram of the pure Sn 2 P 2 S 6 crystal. Several experiments indeed confirmed that the phase transition line splits into two lines after crossing the point with coordinates around p = 0.18 GPa, T = 296 K. The pure Sn 2 P 2 S 6 system is obviously even more attractive than the x = 0.28 compound where, in principle, the LP-related phenomena could be obscured by compositional fluctuations inherent to solid solutions.…”

Section: Introductionmentioning

confidence: 99%

Neutron scattering study of ferroelectric Sn2P2S6under pressure

et al. 2012

View full text Add to dashboard Cite

Ferroelectric phase transition in the semiconductor Sn 2 P 2 S 6 single crystal has been studied by means of neutron scattering in the pressure-temperature range adjacent to the anticipated tricritical Lifshitz point (p ≈ 0.18 GPa, T ≈ 296 K). The observations reveal a direct ferroelectric-paraelectric phase transition in the whole investigated pressure range (0.18-0.6 GPa). These results are in a clear disagreement with phase diagrams assumed in numerous earlier works, according to which a hypothetical intermediate incommensurate phase extends over several or even tens of degrees in the 0.5 GPa pressure range. Temperature dependence of the anisotropic quasielastic diffuse scattering suggests that polarization fluctuations present above T C are strongly reduced in the ordered phase. Still, the temperature dependence of the (200) Bragg reflection intensity at p = 0.18 GPa can be remarkably well modeled assuming the order-parameter amplitude growth according to the power law with logarithmic corrections predicted for a uniaxial ferroelectric transition at the tricritical Lifshitz point.

show abstract

“…On the other hand, the jumps present in the Sn P Se (1), SbSJ (2) and 2 2 6 Sn P S (3) at atm p p = [35]. at the Lifshitz point (see [38]). This coincides with the result calculated theoretically in the mean-field approximation for the universality class UL [39].…”

Section: Experimental Determination Of Temperature and Baric Dependenmentioning

confidence: 99%

Optical properties of A2B2C6 ferroelectrics-semiconductors: the effect of temperature and hydrostatic pressure

Герзанич¹

2008

Ukr. J. Phys. Opt.

View full text Add to dashboard Cite

In this review the results of experimental studies for the influence of temperature and high pressure on the fundamental absorption edge, optical birefringence and vibrational spectra of IV V VI 2 2 6A B C -group crystals are presented. It is revealed that the high-energy part of the absorption edge is described by the Urbach rule, while its low-energy part is formed by indirect optical transitions. Violation of the Urbach rule is detected in the region of incommensurate phase. The temperature and baric coefficients of the forbidden gap in the ferroelectric, paraelectric and incommensurate phases are found to be negative. Electronphonon interaction plays a major part in the temperature changes of the bandgap. According to the theory, the bandgap suffers characteristic anomalies that depend upon the phase transition order. The critical indices of the order parameter and heat capacity and the Landau-Ginzburg expansion coefficients derived from the baric studies of optical birefringence agree well with a presence of Lifshitz point at the р,Т-diagrams of the crystals under test. Relative shift in the frequencies of the Raman spectra occurring under mechanical stresses testifies a notable nonequivalence of atomic bonds and a possibility of dividing the vibrations in Sn 2 P 2 S 6 into the external and internal ones. The results of baric investigations of the Raman spectra show that the structural transformation in Sn 2 P 2 S 6 is mainly linked to Sn-S bonds. The results analysed by us testify a possibility for practical applications of Sn 2 P 2 S 6 ferroelectrics as a converter of coherent long-wave radiation into shorter-wave one.

show abstract

Lifshitz points in uniaxial ferroelectrics

Cited by 40 publications

References 10 publications

Lattice dynamics and phase transitions in Sn_{2}P_{2}S(Se)_{6} ferroelectric crystals

Lattice dynamics and phase transitions in Sn_{2}P_{2}S(Se)_{6} ferroelectric crystals

Neutron scattering study of ferroelectric Sn2P2S6under pressure

Optical properties of A2B2C6 ferroelectrics-semiconductors: the effect of temperature and hydrostatic pressure

Contact Info

Product

Resources

About