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Title: Incommensurate charge-stripe correlations in the kagome superconductor CsV3Sb5−xSnx

The class ofAV3Sb5(A=K, Rb, Cs) kagome metals hosts unconventional charge density wave states seemingly intertwined with their low temperature superconducting phases. The nature of the coupling between these two states and the potential presence of nearby, competing charge instabilities however remain open questions. This phenomenology is strikingly highlighted by the formation of two ‘domes’ in the superconducting transition temperature upon hole-doping CsV3Sb5. Here we track the evolution of charge correlations upon the suppression of long-range charge density wave order in the first dome and into the second of the hole-doped kagome superconductor CsV3Sb5−xSnx. Initially, hole-doping drives interlayer charge correlations to become short-ranged with their periodicity diminished along the interlayer direction. Beyond the peak of the first superconducting dome, the parent charge density wave state vanishes and incommensurate, quasi-1D charge correlations are stabilized in its place. These competing, unidirectional charge correlations demonstrate an inherent electronic rotational symmetry breaking in CsV3Sb5, and reveal a complex landscape of charge correlations within its electronic phase diagram. Our data suggest an inherent 2kfcharge instability and competing charge orders in theAV3Sb5class of kagome superconductors.

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Author(s) / Creator(s):
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Publisher / Repository:
Nature Publishing Group
Date Published:
Journal Name:
npj Quantum Materials
Medium: X
Sponsoring Org:
National Science Foundation
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  1. Abstract

    The recently discovered kagome superconductorsAV3Sb5(A= K, Rb, Cs) exhibit unusual charge-density-wave (CDW) orders with time-reversal and rotational symmetry breaking. One of the most crucial unresolved issues is identifying the symmetry of the superconductivity that develops inside the CDW phase. Theory predicts a variety of unconventional superconducting symmetries with sign-changing and chiral order parameters. Experimentally, however, superconducting phase information inAV3Sb5is still lacking. Here we report the impurity effects in CsV3Sb5using electron irradiation as a phase-sensitive probe of superconductivity. Our magnetic penetration depth measurements reveal that with increasing impurities, an anisotropic fully-gapped state changes to an isotropic full-gap state without passing through a nodal state. Furthermore, transport measurements under pressure show that the double superconducting dome in the pressure-temperature phase diagram survives against sufficient impurities. These results support that CsV3Sb5is a non-chiral, anisotropics-wave superconductor with no sign change both at ambient and under pressure.

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    This work was supported by the U.S. National Science Foundation (NSF) Award No. ECCS-1931088. S.L. and H.W.S. acknowledge the support from the Improvement of Measurement Standards and Technology for Mechanical Metrology (Grant No. 20011028) by KRISS. K.N. was supported by Basic Science Research Program (NRF-2021R11A1A01051246) through the NRF Korea funded by the Ministry of Education.


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    Figure 1


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