Evidence for coupling between charge density waves and phonons in two-dimensional rare-earth tritellurides

Lavagnini, M.; Baldini, Maria; Sacchetti, A.; Castro, D. Di; Delley, B.; Monnier, R.; Chu, J.-H.; Ru, N.; Fisher, I. R.; Postorino, P.; Degiorgi, L.

doi:10.1103/physrevb.78.201101

Cited by 55 publications

(77 citation statements)

References 27 publications

(22 reference statements)

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“…2. The narrow lines superposed on the continuum are the Ramanactive phonons of the high-temperature phase (16). Instead of the expected flat continuum (25), strongly temperature-dependent shoulders, emerging from the normal metallic response, are observed for T CDW1 < T < 300 K in the low-energy part of the spectra ( Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Among them, the prototypical ErTe 3 (Materials and Methods) undergoes a first CDW transition at T CDW1 = 265 K followed by a second one at T CDW2 = 155 K, and it allows a robust access to its intrinsic CDW properties. The ordering vectors Q 1 and Q 2 are parallel to but incommensurate with the reciprocal lattice vectors c* jj c and a* jj a, respectively (11)(12)(13)(14)(15)(16)(17)(18)(19)(20). The electronic properties of these layered CDW compounds can be modeled by considering a single Te plane (Fig.…”

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confidence: 99%

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Alternative route to charge density wave formation in multiband systems

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Lavagnini

Hackl

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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Charge and spin density waves, periodic modulations of the electron, and magnetization densities, respectively, are among the most abundant and nontrivial low-temperature ordered phases in condensed matter. The ordering direction is widely believed to result from the Fermi surface topology. However, several recent studies indicate that this common view needs to be supplemented. Here, we show how an enhanced electron-lattice interaction can contribute to or even determine the selection of the ordering vector in the model charge density wave system ErTe 3 . Our joint experimental and theoretical study allows us to establish a relation between the selection rules of the electronic light scattering spectra and the enhanced electron-phonon coupling in the vicinity of band degeneracy points. This alternative proposal for charge density wave formation may be of general relevance for driving phase transitions into other brokensymmetry ground states, particularly in multiband systems, such as the iron-based superconductors.electron-phonon interactions | nonconventional mechanism | Raman spectroscopy | solid-solid phase transitions T he common view of charge density wave (CDW) formation was originally posed in the work by Kohn (1). Using Kohn's reasoning (1), the tendency to ordering is particularly strong in low dimensions, because the Fermi surface has parallel parts, referred to as nesting. This nesting leads to a divergence in the Lindhard susceptibility, determining the magnitude and direction of the ordering vector Q (2). This divergence in the electronic susceptibility is conveyed to the lattice by the electron-phonon coupling: a phonon softens to zero frequency at Q, and a static lattice distortion develops when the system enters the CDW state, a behavior known as the Kohn anomaly.However, several publications raise the question as to whether nesting alone is sufficient to explain the observed ordering direction Q (3-7), particularly in dimensions higher than 1D. A central question is whether the selection of the CDW ordering vector is always driven by an electronic instability or if the ordering vector could, instead, be determined by a lattice distortion driven by some other mechanism exploiting the role of the electron-phonon coupling. In the latter case, the selected ordering vector would not necessarily nest the Fermi surface. The importance of strongly momentum-dependent electron-phonon coupling on CDW formation was pointed out in refs. 3 and 4, where the relevance of the Fermi surface for determining the ordering vector was indeed found to decrease as the coupling strength increases. In a recent paper on inelastic X-ray scattering measurements on 2H-NbSe 2 , acoustic phonons were observed to soften to zero frequency over an extended region around the CDW ordering vector (8). The authors argue that this behavior is not consistent with a Kohn anomaly picture, where sharp dips are expected (8). Therefore, the phonon softening must be driven by another mechanism, which they identify as a wave vector-dependent e...

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Alternative route to charge density wave formation in multiband systems

Eiter

Lavagnini

Hackl

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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“…The layered RTe 3 compounds exhibit a large anisotropy between the resistivity along the b-axis and that in the (a, c) plane, typically ∼ 10 2 below T CDW 1 and much higher at low temperature 22 . Because the unidirectional character of the upper CDW 19,21,23 , a conductivity anisotropy in the (a, c) plane arises in the CDW state as was observed experimentally and explained theoretically in Ref. 24.…”

Section: Introductionmentioning

confidence: 80%

“…In this space group, the long b axis is perpendicular to the Te planes. These systems exhibit an incommensurate CDW below the Peierls transition temperature T CDW 1 through the whole R series 18,21 , with a wave vector Q CDW 1 = (0, 0, ∼ 2/7c * ) , with T CDW 1 above 300K for the light atoms (La, Ce, Nd). For the heavier R (Tb, Dy, Ho, Er, Tm) atoms a second CDW occurs at low temperature T CDW 2 with the wave vector Q CDW 2 = (∼ 2/7a * , 0, 0) perpendicular to Q CDW 1 .…”

Section: Introductionmentioning

confidence: 99%

“…The effect of the upper CDW on the in-plane resistivity observed in experiments is very weak, no more than a few percents of the total resistance 18,22,24 . Amplitude CDW excitations were probed by Raman spectroscopy 21 , time-resolved ARPES 25 and femtosecond pump-probe spectroscopy 26,27 . This later technique has allowed to study the disentanglement of the electronic and lattice path of the CDW order parameter, the collective vibrations being assigned to amplitude modes.…”

Section: Introductionmentioning

confidence: 99%

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Dynamical properties of bidirectional charge-density waves inErTe3

et al. 2016

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We report a strong difference in the sliding properties of the bidirectional charge density wave (CDW) in the two-dimensional rare earth tritelluride ErTe3 which occurs below TCDW 1 = 265 K with a wave vector along c-axis and below TCDW 2 = 165 K with a wave vector along a-axis; the excess current carried by the motion of the CDW is 10 times less for the lower CDW compared with the value of the upper one. We tentatively explain this result by a stronger pinning of the lower temperature CDW intricated with the upper one, which inhibits its motion and may generate a phase slippage lattice.

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Advances in Rare‐Earth Tritelluride Quantum Materials: Structure, Properties, and Synthesis

Yumigeta

Qin

et al. 2021

Advanced Science

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A distinct class of 2D layered quantum materials with the chemical formula of RTe3 (R = lanthanide) has gained significant attention owing to the occurrence of collective quantum states, superconductivity, charge density waves (CDW), spin density waves, and other advanced quantum properties. To study the Fermi surface nesting driven CDW formation, the layered RTe3 family stages an excellent low dimensional genre system. In addition to the primary energy gap feature observed at higher energy, optical spectroscopy study on some RTe3 evidence a second CDW energy gap structure indicating the occurrence of multiple CDW ordering even with light and intermediate RTe3 compounds. Here, a comprehensive review of the fundamentals of RTe3 layered tritelluride materials is presented with a special focus on the recent advances made in electronic structure, CDW transition, superconductivity, magnetic properties of these unique quantum materials. A detailed description of successful synthesis routes including the flux method, self‐flux method, and CVT along with potential applications is summarized.

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Evidence for coupling between charge density waves and phonons in two-dimensional rare-earth tritellurides

Cited by 55 publications

References 27 publications

Alternative route to charge density wave formation in multiband systems

Alternative route to charge density wave formation in multiband systems

Dynamical properties of bidirectional charge-density waves inErTe3

Advances in Rare‐Earth Tritelluride Quantum Materials: Structure, Properties, and Synthesis

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