Fully-gapped superconductivity with rotational symmetry breaking in pressurized kagome metal CsV3Sb5

Abstract The discovery of the kagome metal CsV3Sb5 has generated significant interest in its complex physical properties, particularly its superconducting behavior under different pressures, though its nature remains debated. Here, we performed low-temperature, high-pressure 121/123Sb nuclear quadru...

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Main Authors: X. Y. Feng, Z. Zhao, J. Luo, Y. Z. Zhou, J. Yang, A. F. Fang, H. T. Yang, H.-J. Gao, R. Zhou, Guo-qing Zheng
Format: Article
Language:English
Published: Nature Portfolio 2025-04-01
Series:Nature Communications
Online Access:https://doi.org/10.1038/s41467-025-58941-w
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author X. Y. Feng
Z. Zhao
J. Luo
Y. Z. Zhou
J. Yang
A. F. Fang
H. T. Yang
H.-J. Gao
R. Zhou
Guo-qing Zheng
author_facet X. Y. Feng
Z. Zhao
J. Luo
Y. Z. Zhou
J. Yang
A. F. Fang
H. T. Yang
H.-J. Gao
R. Zhou
Guo-qing Zheng
author_sort X. Y. Feng
collection DOAJ
description Abstract The discovery of the kagome metal CsV3Sb5 has generated significant interest in its complex physical properties, particularly its superconducting behavior under different pressures, though its nature remains debated. Here, we performed low-temperature, high-pressure 121/123Sb nuclear quadrupole resonance (NQR) measurements to explore the superconducting pairing symmetry in CsV3Sb5. At ambient pressure, we found that the spin-lattice relaxation rate 1/T 1 exhibits a kink at T ~ 0.4 T c within the superconducting state and follows a T 3 variation as temperature further decreases. This suggests the presence of two superconducting gaps with line nodes in the smaller one. As pressure increases beyond P c ~ 1.85 GPa, where the charge-density wave phase is completely suppressed, 1/T 1 shows no Hebel-Slichter peak just below T c, and decreases rapidly, even faster than T 5, indicating that the gap is fully opened for pressures above P c. In this high pressure region, the angular dependence of the in-plane upper critical magnetic field H c2 breaks the C 6 rotational symmetry. We propose the s + i d pairing at P > P c which explains both the 1/T 1 and H c2 behaviors. Our findings indicate that CsV3Sb5 is an unconventional superconductor and its superconducting state is even more exotic at high pressures.
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spelling doaj-art-0eb263cdbb0145ceaba86f07e206744d2025-08-20T03:18:32ZengNature PortfolioNature Communications2041-17232025-04-011611810.1038/s41467-025-58941-wFully-gapped superconductivity with rotational symmetry breaking in pressurized kagome metal CsV3Sb5X. Y. Feng0Z. Zhao1J. Luo2Y. Z. Zhou3J. Yang4A. F. Fang5H. T. Yang6H.-J. Gao7R. Zhou8Guo-qing Zheng9Institute of Physics, Chinese Academy of Sciences, and Beijing National Laboratory for Condensed Matter PhysicsInstitute of Physics, Chinese Academy of Sciences, and Beijing National Laboratory for Condensed Matter PhysicsInstitute of Physics, Chinese Academy of Sciences, and Beijing National Laboratory for Condensed Matter PhysicsInstitute of Physics, Chinese Academy of Sciences, and Beijing National Laboratory for Condensed Matter PhysicsInstitute of Physics, Chinese Academy of Sciences, and Beijing National Laboratory for Condensed Matter PhysicsSchool of Physics and Astronomy, Beijing Normal UniversityInstitute of Physics, Chinese Academy of Sciences, and Beijing National Laboratory for Condensed Matter PhysicsInstitute of Physics, Chinese Academy of Sciences, and Beijing National Laboratory for Condensed Matter PhysicsInstitute of Physics, Chinese Academy of Sciences, and Beijing National Laboratory for Condensed Matter PhysicsDepartment of Physics, Okayama UniversityAbstract The discovery of the kagome metal CsV3Sb5 has generated significant interest in its complex physical properties, particularly its superconducting behavior under different pressures, though its nature remains debated. Here, we performed low-temperature, high-pressure 121/123Sb nuclear quadrupole resonance (NQR) measurements to explore the superconducting pairing symmetry in CsV3Sb5. At ambient pressure, we found that the spin-lattice relaxation rate 1/T 1 exhibits a kink at T ~ 0.4 T c within the superconducting state and follows a T 3 variation as temperature further decreases. This suggests the presence of two superconducting gaps with line nodes in the smaller one. As pressure increases beyond P c ~ 1.85 GPa, where the charge-density wave phase is completely suppressed, 1/T 1 shows no Hebel-Slichter peak just below T c, and decreases rapidly, even faster than T 5, indicating that the gap is fully opened for pressures above P c. In this high pressure region, the angular dependence of the in-plane upper critical magnetic field H c2 breaks the C 6 rotational symmetry. We propose the s + i d pairing at P > P c which explains both the 1/T 1 and H c2 behaviors. Our findings indicate that CsV3Sb5 is an unconventional superconductor and its superconducting state is even more exotic at high pressures.https://doi.org/10.1038/s41467-025-58941-w
spellingShingle X. Y. Feng
Z. Zhao
J. Luo
Y. Z. Zhou
J. Yang
A. F. Fang
H. T. Yang
H.-J. Gao
R. Zhou
Guo-qing Zheng
Fully-gapped superconductivity with rotational symmetry breaking in pressurized kagome metal CsV3Sb5
Nature Communications
title Fully-gapped superconductivity with rotational symmetry breaking in pressurized kagome metal CsV3Sb5
title_full Fully-gapped superconductivity with rotational symmetry breaking in pressurized kagome metal CsV3Sb5
title_fullStr Fully-gapped superconductivity with rotational symmetry breaking in pressurized kagome metal CsV3Sb5
title_full_unstemmed Fully-gapped superconductivity with rotational symmetry breaking in pressurized kagome metal CsV3Sb5
title_short Fully-gapped superconductivity with rotational symmetry breaking in pressurized kagome metal CsV3Sb5
title_sort fully gapped superconductivity with rotational symmetry breaking in pressurized kagome metal csv3sb5
url https://doi.org/10.1038/s41467-025-58941-w
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