Fermiology and Origin of Tc Enhancement in a Kagome Superconductor Cs(V1-xNbx)3Sb5

Kato, Takemi; Li, Yongkai; Nakayama, K.; Wang, Zhiwei; Souma, S.; Matsui, Fumihiko; Kitamura, Miho; Horiba, Koji; Kumigashira, Hiroshi; Takahashi, Takashi; Yao, Yugui; Sato, Takafumi

doi:10.48550/arxiv.2205.04907

Cited by 2 publications

(2 citation statements)

References 42 publications

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“…As shown in Fig. 3a, the FS topology of the Nb0.07 sample is also similar to that of CsV3Sb5, consisting of the circular a FS, hexagonal b FS and triangular d FS, which is consistent with the previous ARPES measurements 39 and the calculations based on density function theory 40 (supplementary Fig. S3).…”

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confidence: 88%

Nodeless electron pairing in CsV3Sb5-derived kagome superconductors

Zhong

Liu

et al. 2023

Nature

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Nodeless electron pairing in CsV3Sb5-derived kagome superconductorsThe newly discovered kagome superconductors represent a promising platform for investigating the quantum interplay between band topology, electronic order, and lattice geometry 1-8 . Despite extensive research efforts on this system, the nature of the superconducting ground state remains elusive 9-15 . In particular, consensus on the electron pairing symmetry has not been achieved so far [16][17][18] , in part owing to the lack of a momentum-resolved measurement of the superconducting gap structure. Here we report the direct observation of a nodeless, nearly isotropic and orbital-independent superconducting gap in the momentum space of two exemplary CsV3Sb5-derived kagome superconductors -Cs(V0.93Nb0.07)3Sb5 and Cs(V0.86Ta0.14)3Sb5, using ultrahigh resolution and low temperature angle-resolved photoemission spectroscopy (ARPES). Remarkably, we find that such a gap structure is robust to the appearance or absence of charge order in the normal state, tuned by isovalent Nb/Ta substitutions of V. Moreover, the scaling ratio of gap versus superconducting transition temperature is close to the Bardeen-Cooper-Schrieffer (BCS) value, indicating a pairing in the weak-coupling regime. Our direct observation of the superconducting gap structure points to a persistent s-wave pairing in such kagome superconductors.Superconductivity often emerges in the vicinity of other ordered electronic states with a broken symmetry, such as antiferromagnetic order and charge density wave. Their interdependence has been widely studied in cuprate and iron-based superconductors 19,20 , while persists as a key issue for understanding the high temperature superconductivity. In certain cases, the ordered state and superconductivity can even coexist 21,22 , which may indicate an unconventional pairing and have a dramatic impact on the superconducting mechanism.Because of the unique lattice geometry and unusual electronic features in a kagome lattice [1][2][3]23 , the recently discovered kagome superconductors stand out as a new platform for inspecting the superconductivity emerging from a complex landscape of electronic orders 4,5,24,25 . Of particular interest is the nonmagnetic family of AV3Sb5 (A = K, Rb, Cs) 4,6 , in which a variety of intriguing phenomena have been uncovered, including a tantalizing time-reversal symmetry broken charge density wave (CDW) order 7,8,26,27 , a pair density wave 9 , electronic nematicity 8,28-30 ,

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supporting

confidence: 88%

Nodeless electron pairing in CsV3Sb5-derived kagome superconductors

Zhong

Liu

et al. 2023

Nature

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show abstract

supporting

confidence: 88%

Nodeless electron pairing in CsV3Sb5-derived kagome superconductors

Okazaki

Zhong

Liu

et al. 2022

Preprint

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The newly discovered kagome superconductors represent a promising platform for investigating the quantum interplay between band topology, electronic order, and lattice geometry. Despite extensive research efforts on this system, the nature of the superconducting ground state remains elusive. In particular, consensus on the electron pairing symmetry has not been achieved so far, in part owing to the lack of a momentum-resolved measurement of the superconducting gap structure. Here we report the direct observation of a nodeless, nearly isotropic and orbital-independent superconducting gap in the momentum space of two exemplary CsV3Sb5-derived kagome superconductors — Cs(V0.93Nb0.07)3Sb5 and Cs(V0.86Ta0.14)3Sb5, using ultrahigh resolution and low temperature angle-resolved photoemission spectroscopy (ARPES). Remarkably, we find that such a gap structure is robust to the appearance or absence of charge order in the normal state, tuned by isovalent Nb/Ta substitutions of V. Moreover, the scaling ratio of gap versus superconducting transition temperature is close to the Bardeen-Cooper-Schrieffer (BCS) value, indicating a pairing in the weak-coupling regime. Our direct observation of the superconducting gap structure points to a persistent s-wave pairing in such kagome superconductors.

show abstract

Fermiology and Origin of Tc Enhancement in a Kagome Superconductor Cs(V1-xNbx)3Sb5

Cited by 2 publications

References 42 publications

Nodeless electron pairing in CsV3Sb5-derived kagome superconductors

Nodeless electron pairing in CsV3Sb5-derived kagome superconductors

Nodeless electron pairing in CsV3Sb5-derived kagome superconductors

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