Absence of local moments in the kagome metal KV<sub>3</sub>Sb<sub>5</sub> as determined by muon spin spectroscopy

Kenney, Eric; Ortiz, Brenden R.; Wang, Chennan; Wilson, Stephen D.; Graf, M. J.

doi:10.1088/1361-648x/abe8f9

Cited by 147 publications

(84 citation statements)

References 26 publications

(52 reference statements)

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“…CsV 3 Sb 5 features Z 2 band topology and a two-stage symmetry breaking: a CDW transition at T CDW ∼ 95 K with a subsequent superconducting transition at T C ∼ 2.7 K 10-14 . The CDW order with inverse star-of-David pattern involves 2 × 2 and concurs with the CDW order despite the lack of long-range magnetic ordering 10, 12,15,[17][18][19] .…”

Section: Introductionsupporting

confidence: 57%

Fermi surface instabilities in electronic Raman scattering of the metallic kagome lattice CsV3Sb5

Wulferding¹,

Lee²,

Choi³

et al. 2021

Preprint

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Understanding the link between a charge density wave (CDW) instability and superconductivity is a central theme of the 2D metallic kagome compounds AV3Sb5 (A=K, Rb, and Cs). Using polarization-resolved electronic Raman spectroscopy, we shed light on Fermi surface fluctuations and electronic instabilities. We observe a quasielastic peak (QEP) whose spectral weight is progressively enhanced towards the superconducting transition. The QEP temperature-dependence reveals a steep increase in coherent in-plane charge correlations within the charge-density phase. In contrast, out-of-plane charge fluctuations remain strongly incoherent across the investigated temperature range. In-plane phonon anomalies appear at T* ≈ 50 K in addition to right below TCDW ≈ 95 K, while showing no apparent evidence of reduced symmetry at low temperatures. In conjunction with the consecutive phonon anomalies within the CDW state, our electronic Raman data unveil additional electronic instabilities that persist down to the superconducting phase, thereby offering a superconducting mechanism.

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Section: Introductionsupporting

confidence: 57%

Fermi surface instabilities in electronic Raman scattering of the metallic kagome lattice CsV3Sb5

Wulferding¹,

Lee²,

Choi³

et al. 2021

Preprint

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“…Since the present muon spin rotation experiments show direct evidence for the absence of local moments of the Ru atom in LaRu 3 Si 2 , this kagome system is different from high-T c superconductors or spin liquid compounds. It is rather on the side of itinerant kagome or hexagonal systems such as (Cs,K)V 3 Sb 5 [53] or even 2H-NbSe 2 [46], where μSR shows the absence of magnetic correlations. On the other hand, the system LaRu 3 Si 2 does not exhibit a CDW ground state unlike the superconductors (Cs,K)V 3 Sb 5 [54].…”

Section: Resultsmentioning

confidence: 99%

Nodeless kagome superconductivity in LaRu3Si2

Mielke

Qin

Yin

et al. 2021

Phys. Rev. Materials

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We report muon spin rotation (μSR) experiments together with first-principles calculations on microscopic properties of superconductivity in the kagome superconductor LaRu 3 Si 2 with T c 7K. Below T c , μSR reveals type-II superconductivity with a single s-wave gap, which is robust against hydrostatic pressure up to 2 GPa. We find that the calculated normal state band structure features a kagome flat band, and Dirac as well as van Hove points formed by the Ru-dz 2 orbitals near the Fermi level. We also find that electron-phonon coupling alone can only reproduce a small fraction of T c from calculations, which suggests other factors in enhancing T c such as the correlation effect from the kagome flat band, the van Hove point on the kagome lattice, and the high density of states from narrow kagome bands. Our experiments and calculations taken together point to nodeless moderate coupling kagome superconductivity in LaRu 3 Si 2 .

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“…The superconducting transition temperature Tc is 0.93, 0.92, and 2.5 K for A = K, Rb, and Cs, respectively [2][3][4] . While there are no local magnetic moments 12 , these V-based superconductors manifest a charge density wave (CDW) order at 78, 103, and 94 K, respectively [1][2][3][4] . Interestingly, for KV3Sb5, high-resolution scanning tunneling microscopy (STM) study demonstrated that such charge order in the frustrated Kagome lattice is topological 5 , which leads to a giant anomalous Hall effect 6 , and can also be a strong precursor of unconventional superconductivity 5 .…”

Section: Introductionmentioning

confidence: 99%

Nodal superconductivity and superconducting domes in the topological Kagome metal CsV3Sb5

Li¹,

Zhao²,

Wang³

et al. 2021

Preprint

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Recently superconductivity was discovered in the Kagome metal AV3Sb5 (A = K, Rb, and Cs), which has an ideal Kagome lattice of vanadium1-4. These V-based superconductors also host charge density wave (CDW)5 and topological nontrivial band structure2,6, thus provide a great platform to study the interplay of superconductivity, CDW, frustration, and topology. Here we report the ultralow-temperature thermal conductivity and high pressure resistance measurements on CsV3Sb5 with Tc ≈ 2.5 K, the highest among AV3Sb5. A finite residual linear term of thermal conductivity at zero magnetic field and its rapid increase in fields suggest nodal superconductivity. By applying pressure, the Tc of CsV3Sb5 increases first, then decreases to lower than 0.3 K at 11.4 GPa, demonstrating a clear first superconducting dome peaked around 0.8 GPa. Above 11.4 GPa, superconductivity re-emerges, showing a second superconducting dome. Both nodal superconductivity and superconducting domes point to unconventional superconductivity in this V-based superconductor. While our finding of nodal superconductivity puts a strong constrain on the pairing state of the first dome, which should be related to the CDW instability, the superconductivity of the second dome may present another exotic pairing state in this ideal Kagome lattice of vanadium.

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Absence of local moments in the kagome metal KV₃Sb₅ as determined by muon spin spectroscopy

Cited by 147 publications

References 26 publications

Fermi surface instabilities in electronic Raman scattering of the metallic kagome lattice CsV3Sb5

Fermi surface instabilities in electronic Raman scattering of the metallic kagome lattice CsV3Sb5

Nodeless kagome superconductivity in LaRu3Si2

Nodal superconductivity and superconducting domes in the topological Kagome metal CsV3Sb5

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Absence of local moments in the kagome metal KV3Sb5 as determined by muon spin spectroscopy

Cited by 147 publications

References 26 publications

Fermi surface instabilities in electronic Raman scattering of the metallic kagome lattice CsV3Sb5

Fermi surface instabilities in electronic Raman scattering of the metallic kagome lattice CsV3Sb5

Nodeless kagome superconductivity in LaRu3Si2

Nodal superconductivity and superconducting domes in the topological Kagome metal CsV3Sb5

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Absence of local moments in the kagome metal KV₃Sb₅ as determined by muon spin spectroscopy