Charge Density Waves and Electronic Properties of Superconducting Kagome Metals

Tan, Hengxin; Liu, Yizhou; Wang, Ziqiang; Yan, Binghai

doi:10.1103/physrevlett.127.046401

Cited by 373 publications

(325 citation statements)

References 37 publications

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“…The observed kink in the energy dispersion and the peak-dip-hump structure in EDCs are reminiscent of those from the electron–boson coupling in simple metal 46 and high-temperature superconductors 47 . The phonon frequency of the vanadium vibrations in AV 3 Sb 5 can reach up to ~36 meV 32 that is consistent with the mode energy we have observed. Therefore, we have observed significant self-energy effects in KV 3 Sb 5 .…”

Section: Resultssupporting

confidence: 91%

“…Besides the Fermi surface nesting, the CDW phase can also be driven by the concerted action of electronic and ionic subsystems where a q -dependent electron–phonon coupling plays an indispensable part 49 , 50 . In AV 3 Sb 5 system, the driving force for the CDW formation remains under debate 15 , 17 , 25 , 32 , 33 , 37 , 38 . Based on our observations, we found that the electron–phonon coupling plays a major role in generating the CDW phase in KV 3 Sb 5 .…”

Section: Discussionmentioning

confidence: 99%

“…The CDW state shows an unusual magnetic response 15 that is intimately related to the anomalous Hall effect 13 and competes with superconductivity under pressure 26 – 31 . Understanding the electronic structure of the CDW state is essential to reveal its nature and relation to the topological state and superconductivity 25 , 32 – 36 . However, little is known about the impact of the CDW state on the electronic structure in AV 3 Sb 5 37 – 39 .…”

Section: Introductionmentioning

confidence: 99%

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Electronic nature of charge density wave and electron-phonon coupling in kagome superconductor KV3Sb5

et al. 2022

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The Kagome superconductors AV3Sb5 (A = K, Rb, Cs) have received enormous attention due to their nontrivial topological electronic structure, anomalous physical properties and superconductivity. Unconventional charge density wave (CDW) has been detected in AV3Sb5. High-precision electronic structure determination is essential to understand its origin. Here we unveil electronic nature of the CDW phase in our high-resolution angle-resolved photoemission measurements on KV3Sb5. We have observed CDW-induced Fermi surface reconstruction and the associated band folding. The CDW-induced band splitting and the associated gap opening have been revealed at the boundary of the pristine and reconstructed Brillouin zones. The Fermi surface- and momentum-dependent CDW gap is measured and the strongly anisotropic CDW gap is observed for all the V-derived Fermi surface. In particular, we have observed signatures of the electron-phonon coupling in KV3Sb5. These results provide key insights in understanding the nature of the CDW state and its interplay with superconductivity in AV3Sb5 superconductors.

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Section: Resultssupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electronic nature of charge density wave and electron-phonon coupling in kagome superconductor KV3Sb5

et al. 2022

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“…Previous first-principles calculation [28,41] in AV 3 Sb 5 has also confirmed that the 2 × 2 charge order is a bulk effect and is consistent with a hexamer and trimer formation [28] (or termed as inverse star of David formation [41]) in the V kagome lattice. The chirality feature of the charge order, however, is beyond the current first-principles calculation.…”

Section: Transport and Tunneling Resultssupporting

confidence: 61%

Electronic nature of chiral charge order in the kagome superconductor CsV3Sb5

et al. 2021

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Kagome superconductors with T C up to 7 K have been discovered for over 40 y. Recently, unconventional chiral charge order has been reported in kagome superconductor KV 3 Sb 5 , with an ordering temperature of one order of magnitude higher than the T C . However, the chirality of the charge order has not been reported in the cousin kagome superconductor CsV 3 Sb 5 , and the electronic nature of the chirality remains elusive. In this paper, we report the observation of electronic chiral charge order in CsV 3 Sb 5 via scanning tunneling microscopy (STM). We observe a 2 × 2 charge modulation and a 1 × 4 superlattice in both topographic data and tunneling spectroscopy. 2 × 2 charge modulation is highly anticipated as a charge order by fundamental kagome lattice models at van Hove filling, and is shown to exhibit intrinsic chirality. We find that the 1 × 4 superlattices form various small domain walls, and can be a surface effect as supported by our first-principles calculations. Crucially, we find that the amplitude of the energy gap opened by the charge order exhibits real-space modulations, and features 2 × 2 wave vectors with chirality, highlighting the electronic nature of the chiral charge order. STM study at 0.4 K reveals a superconducting energy gap with a gap size 2 = 0.85 meV, which estimates a moderate superconductivity coupling strength with 2 /k B T C = 3.9. When further applying a c-axis magnetic field, vortex core bound states are observed within this gap, indicative of clean-limit superconductivity.

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“…4(d)], with the leading instability at the L point. These phonon instabilities are B 1u modes, corresponding to a CDW state with a star of David (or its inverse) deformation of the kagome lattice [45], consistent with previous calculations for AV 3 Sb 5 [39,44]. Increasing pressure to 10 GPa in RbV 3 Sb 5 and 5 GPa in KV 3 Sb 5 [Figs.…”

Section: First-principles Calculations Of Phonon Spectrasupporting

confidence: 88%

Superconductivity modulated by structural phase transitions in pressurized vanadium-based kagome metals

Du¹,

Li²,

Luo³

et al. 2021

Preprint

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The interplay of superconductivity with electronic and structural instabilities on the kagome lattice provides a fertile ground for the emergence of unusual phenomena. The vanadium-based kagome metals AV3Sb5 (A = K, Rb, Cs) exhibit superconductivity on an almost ideal kagome lattice, with the superconducting transition temperature Tc forming two domes upon pressure-tuning. The first dome arises from the competition between superconductivity and a charge-density-wave, whereas the origin for the second dome remains unclear. Herein, we show that the appearance of the second superconducting dome in KV3Sb5 and RbV3Sb5 is associated with transitions from hexagonal P6/mmm to monoclinic P2/m structures, evidenced by splitting of structural peaks from synchrotron powder X-ray diffraction experiments and imaginary phonon frequencies in first-principles calculations. In KV3Sb5, transition to an orthorhombic Pmmm structure is further observed for pressure p≥20 GPa, and is correlated with the strong suppression of Tc in the second superconducting dome. Our findings indicate distortions of the crystal structure modulates superconductivity in AV3Sb5 under pressure, providing a platform to study the emergence of superconductivity in the presence of multiple structural instabilities.

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Charge Density Waves and Electronic Properties of Superconducting Kagome Metals

Cited by 373 publications

References 37 publications

Electronic nature of charge density wave and electron-phonon coupling in kagome superconductor KV3Sb5

Electronic nature of charge density wave and electron-phonon coupling in kagome superconductor KV3Sb5

Electronic nature of chiral charge order in the kagome superconductor CsV3Sb5

Superconductivity modulated by structural phase transitions in pressurized vanadium-based kagome metals

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