Order-disorder charge density wave instability in the kagome metal (Cs,Rb)V3Sb5

Subires, David; A., Korshunov,; Said, Ayman; L., Sánchez,; Ortiz, Brenden R.; Wilson, Stephen D.; Bosak, Alexeï; Blanco-Canosa, S.

doi:10.1038/s41467-023-36668-w

Cited by 28 publications

(18 citation statements)

References 55 publications

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“…The thermal conductivity even drops below the Cahill-Pohl limit below TCDW 35 . Our observation is aligned with the observation that localized phonon modes drive structural fluctuations near TCDW 26 . Considering these localized modes could be well-described by Einstein oscillators, we proposed a hopping model to describe the cross-plane thermal transport.…”

Section: Synthesis and Preliminary Characterizationsupporting

confidence: 90%

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Glass-like Cross-plane Thermal Conductivity of Kagome Metals RbV3Sb5 and CsV3Sb5

Liu

Xiang

Fan

et al. 2023

Preprint

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This work reports the thermal conductivity of RbV3Sb5 and CsV3Sb5 with three-dimensional charge density wave phase transitions from 80 K to 400 K measured by pump-probe thermoreflectance techniques. At room temperature, the in-plane (basal plane) thermal conductivities are found moderate, i.e., 12 W m-1 K-1 of RbV3Sb5 and 8.8 W m-1 K-1 of CsV3Sb5, and ultralow cross-plane (stacking direction) thermal conductivities are observed, with 0.72 W m-1 K-1 of RbV3Sb5 and 0.49 W m-1 K-1 of CsV3Sb5 at 300 K. A unique glass-like temperature dependence in the cross-plane thermal conductivity is discovered, which decreases monotonically even lower than the Cahill-Pohl limit as the temperature decreases below the phase transition point TCDW. This temperature dependence is found to obey the hopping transport picture. In addition, a peak in cross-plane thermal conductivity is observed at TCDW as a fingerprint of the modulated structural distortion along the stacking direction.

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Section: Synthesis and Preliminary Characterizationsupporting

confidence: 90%

“…recently proposed that CDW phase change in AV3Sb5 is of order-disorder type which goes beyond the conventional weak-coupling regime of Peierls transitions 26 .…”

Section: Introductionmentioning

confidence: 96%

Glass-like Cross-plane Thermal Conductivity of Kagome Metals RbV3Sb5 and CsV3Sb5

Liu

Xiang

Fan

et al. 2023

Preprint

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“…While such phonon softening is limited to small range in momentum in Peierls' model, it occurs over an extended range in 2H-NbSe 2 and BaNi 2 As 2 , similar to the observed behavior of q * -CDW in ScV 6 Sn 6 . On the other hand, orderdisorder CDW transitions have been reported in systems such as (Ca 1−x Sr x ) 3 Rh 4 Sn 13 [67] and AV 3 Sb 5 [56], and likely characterizes the formation of q s -CDW in ScV 6 Sn 6 . Thus, the CDW formation process in ScV 6 Sn 6 is unique in that both prominent phonon softening and the growth of a central peak are observed, with the two effects associated with different wavevectors, a result of competing CDW instabilities.…”

Section: Discussionmentioning

confidence: 99%

“…Phonons play crucial roles in the CDWs of the kagome metals AV 3 Sb 5 and FeGe, and understanding their be-2 haviors offered critical insights regarding the mechanism underlying CDW formation [41,[55][56][57]. Whereas CDWs in both the weak-and strong-coupling limits are expected to exhibit soft phonons above the CDW ordering temperature, inelastic X-ray scattering (IXS) measurements of AV 3 Sb 5 reveal an absence of such phonon softening, suggesting an unconventional CDW near the van Hove filling [41,56]. Inelastic neutron scattering unveils the hardening of a longitudinal optical phonon inside the CDW state of CsV 3 Sb 5 , implicating a key role of electron-phonon coupling (EPC) in the CDW formation [55].…”

Section: Introductionmentioning

confidence: 99%

Competing charge-density wave instabilities in the kagome metal ScV6Sn6

Song

Cao

et al. 2023

Preprint

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Owing to its unique geometry, the kagome lattice hosts various many-body quantum states including frustrated magnetism, superconductivity, charge-density waves (CDWs), and topologically nontrivial phases of matter. Kagome metals with 2×2 CDWs, corresponding to the nesting of van Hove saddle points, are found to exhibit a number of exotic electronic phases, and have been the focus of much recent research. More recently, a √3×√3 CDW was discovered in the kagome metal ScV6Sn6 below TCDW≈91 K, whose underlying mechanism and formation process remain unclear, particularly in comparison with the 2×2 kagome CDWs. Using inelastic X-ray scattering, we discover a short-range √3×√3×2 CDW that is dominant in ScV6Sn6 well above TCDW, distinct from the √3×√3×3 CDW below TCDW. The short-range CDW grows upon cooling, and is accompanied by the softening of phonons, indicative of its dynamic nature. As the √3×√3×3 CDW appears, the short-range CDW becomes suppressed, revealing a competition between these CDW instabilities. The competing CDW instabilities in ScV6Sn6 lead to an unusual CDW formation process, with the most pronounced phonon softening and the static CDW occurring at different wavevectors. Our first-principles calculations indicate that the √3×√3×2 CDW is energetically favored, consistent with experimental observations at high temperatures. However, the √3×√3×3 CDW is selected as the ground state due to a large wavevector-dependent electron-phonon coupling (EPC), which also accounts for the enhanced electron scattering above TCDW. Our findings reveal the dominance of EPC-driven correlated many-body physics in ScV6Sn6, making it an ideal system to study emergent quantum matter in the strong EPC regime.

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“…For a second order Peierls transition it is thus predicted that the critical dynamics in the anti-adiabatic regime consists in the divergent growth of a zero-energy response when T P is approached (right part of figure 40). Such an elastic scattering has been explicitly observed at the CDW transition of BaVS 3 [291] and (Cs,Rb)V 3 Sb 5 [294].…”

Section: Anti-adiabatic Regimementioning

confidence: 72%

Structural approach to charge density waves in low-dimensional systems: electronic instability and chemical bonding

Pouget,

Canadell

2024

Rep. Prog. Phys.

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Abstract. The charge density wave (CDW) instability, usually occurring in low-dimensional materials, has been a topic of interest for longtime. However, some very fundamental aspects of the mechanism remain unclear. Recently, a plethora of new CDW materials, a substantial fraction of which is 2D (two-dimensional) or even 3D (three-dimensional), has been prepared and characterized as bulk and/or single-layers. As a result, the need for revisiting the primary mechanism of the instability, based on the electron-hole instability established more than 50 years ago for quasi-1D (quasi-one-dimensional) conductors, has clearly emerged. In this work, we consider a large number of CDW materials to revisit the main concepts used in understanding the CDW instability, and emphasize the key role of the momentum dependent electron-phonon coupling in linking electronic and structural degrees of freedom. We argue that for quasi-1D systems, earlier weak coupling theories work appropriately and the energy gain due to the CDW and the concomitant periodic lattice distortion (PLD) remains primarily due to a Fermi surface nesting mechanism. However, for materials with higher dimensionality, intermediate and strong coupling regimes are generally at work and the modification of the chemical bonding network by the PLD is at the heart of the instability. We emphasize the need for a microscopic approach blending condensed matter physics concepts and state-of-the-art first-principles calculations with quite fundamental chemical bonding ideas in understanding the CDW phenomenon in these materials.

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Order-disorder charge density wave instability in the kagome metal (Cs,Rb)V3Sb5

Cited by 28 publications

References 55 publications

Glass-like Cross-plane Thermal Conductivity of Kagome Metals RbV3Sb5 and CsV3Sb5

Glass-like Cross-plane Thermal Conductivity of Kagome Metals RbV3Sb5 and CsV3Sb5

Competing charge-density wave instabilities in the kagome metal ScV6Sn6

Structural approach to charge density waves in low-dimensional systems: electronic instability and chemical bonding

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