Nature of the Peierls transition in charge density wave systems: Strong coupling versus weak coupling

Monçeau, P.

doi:10.1016/j.physd.2006.01.016

Cited by 5 publications

(4 citation statements)

References 19 publications

(23 reference statements)

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“…Common to all these materials is that a resolution-limited "central" peak appears at the elastic position without a phonon softening to zero energy, which it is understood as defect-induced nucleation of finite-size domains of the low-temperature phase. While in general the nature of the lattice defects responsible for the central peak in these materials has remained undetermined, a model in the strong coupling regime for quasi 1D material, e.g., NbSe3 and (TaSe4)2I, has been proposed by Aubry, Abramovici and Raimbault [46] and was used to explain experimental results from inelastic x-ray scattering in these materials [47,48].…”

Section: Discussionmentioning

confidence: 99%

Competing soft phonon modes at the charge-density-wave transitions in DyTe3

et al. 2018

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The family of rare-earth tritellurides RTe3 features charge-density-wave (CDW) order related to strongly momentum-dependent electron-phonon coupling. Similar to other CDW compounds, superconductivity is observed when the CDW order is suppressed via hydrostatic pressure [1]. What sets the heavier members of the RTe3 series apart is the observation of a second CDW transition at lower temperatures having an in-plane ordering wavevector , ∥ [ ] of almost the same magnitude but orthogonal to the ordering wavevector , ∥ [ ] observed at higher temperatures [2]. Here, we report an inelastic x-ray scattering investigation of the lattice dynamics of DyTe3. In particular, we show that there are several phonon modes along both in-plane directions, which respond to the onset of the CDW transition at , =. Surprisingly, these soft modes close to , = ( . , , ) show strong softening near , but do not exhibit any response to the lower-temperature transition at , = . Our results indicate that the low-temperature CDW order is not just the 90° rotated analogue of the one appearing at high temperatures.

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Section: Discussionmentioning

confidence: 99%

Competing soft phonon modes at the charge-density-wave transitions in DyTe3

et al. 2018

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“…For that reason, it remains essential to understand their origin and their physical properties. Many experiments show evidences of strong e-p coupling in a lot of one and two-dimensional CDW systems [2][3][4][5]. In this respect, the new quasi twodimensional rare-earth tritellurides (ReTe 3 , where Re=rare-earth) appear nowadays among the most convaincing.…”

Section: Introductionmentioning

confidence: 99%

Theory of charge density wave depinning by electromechanical effect

Quemerais¹

2017

EPL

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We discuss the first theory for the depinning of low dimensional, incommensurate, charge density waves (CDWs) in the strong electron-phonon (e-p) regime. Arguing that most real CDWs systems invariably develop a gigantic dielectric constant (GDC) at very low frequencies, we propose an electromechanical mechanism which is based on a local field effect. At zero electric field and large enough e-p coupling the structures are naturally pinned by the lattice due to its discreteness, and develop modulation functions which are characterized by discontinuities. When the electric field is turned on, we show that it exists a finite threshold value for the electric field above which the discontinuities of the modulation functions vanish due to CDW deformation. The CDW is then free to move. The signature of this pinning/depinning transition as a function of the increasing electric field can be directly observed in the phonon spectrum by using inelastic neutrons or X-rays experiments.

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“…S1); this peculiarity is readily understood, given that the enhanced dimerization fluctuations would lead to a pseudo-spingap well above T c in analogy with the pseudo-charge-gap in some charge-Peierls systems 27 . In the light of the strong electron-phonon coupling discussed in the charge-Peierls transition 28 , the two distinct results described above are attributable to strong spinphonon coupling, which may be characteristic of organic donoracceptor-type ferroelectric spin-Peierls system such as TTF-BA.…”

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confidence: 99%

Ferroelectricity in a one-dimensional organic quantum magnet

et al. 2010

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In magnetically controllable ferroelectrics 1-3 , electric polarization is induced by charge redistribution or lattice distortions that occur to minimize the energy associated with both the magnetic order and interaction of spins with an applied magnetic field. Conventional approaches to designing materials that exploit such spin-mediated behaviour have focused mainly on developing the cycloidal spin order 4,5 , and thereby producing ferroelectric behaviour through the so-called antisymmetric Dzyaloshinskii-Moriya interaction 6-8. However, engineering such spin structures is challenging. Here we suggest a different approach. Direct measurements of magnetic-field-dependent variations in the polarization of the one-dimensional organic quantum magnet, tetrathiafulvalene-p-bromanil, suggest a spin-Peierls instability has an important role in its response. Our results imply that one-dimensional quantum magnets, such as organic charge-transfer complexes, could be promising candidates in the development of magnetically controllable ferroelectric materials. A straightforward guideline for designing spin-driven ferroelectricity might be to use the symmetric interaction, simply because it is more dominant in ubiquitous magnets, rather than the antisymmetric exchange interaction (that is, the Dzyaloshinskii-Moriya interaction). In this context, the up-up-down-down (↑↑↓↓) magnetic order on the alternating (ABAB) atom sites was proposed as a promising candidate for symmetric-exchange-driven ferroelectricity 9 ; this prediction has actually been confirmed in the frustrated Ising chain system, Ca 3 Co 2−x Mn x O 6 (A = Co and B = Mn) 10 , and the f-d spin-coupled state of GdFeO 3 (A = Gd and B = Fe) 11. Moreover, there is a theoretical argument that symmetric-exchange-driven ferroelectricity can host potentially large polarization 12. This recent progress is prompting a pursuit of not only materials showing the ↑↑↓↓ order but also other clear-cut examples of symmetric-exchange-driven ferroelectricity. In the same way as one-dimensional (1D) metals with inherent lattice instability (Peierls instability) 13 , 1D Heisenberg spin-1/2 quantum magnets possess an instability to form a dimer-singlet state because of the energy gain of symmetric exchange 14,15. This is known as the spin-Peierls instability, a textbook example of spin-lattice coupling. Therefore, the spin-Peierls instability with alternating ABAB spin sites can host a polar singlet-dimer and hence is expected to provide a new mechanism for magnetically controllable ferroelectrics of symmetric-exchange origin. The organic charge-transfer salt TTF-BA (tetrathiafulvalene-p-bromanil) has been proposed as a possible candidate of this new class 16 of material, namely a ferroelectric spin-Peierls material; nevertheless, direct observations of ferroelectricity, that is, electric-field reversal of polarization, have LETTERS NATURE PHYSICS

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Nature of the Peierls transition in charge density wave systems: Strong coupling versus weak coupling

Cited by 5 publications

References 19 publications

Competing soft phonon modes at the charge-density-wave transitions in DyTe3

Competing soft phonon modes at the charge-density-wave transitions in DyTe3

Theory of charge density wave depinning by electromechanical effect

Ferroelectricity in a one-dimensional organic quantum magnet

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