Phase-sensitive evidence for pair density waves in a kagome superconductor

Pair density wave (PDW) exhibits periodic amplitude and sign modulations of the superconducting order parameter. Such a pairing state has long been proposed to be highly sensitive to nonmagnetic scattering, but its experimental realization remains elusive. Here, we find a nonmagnetic PDW-breaking effect in a kagome superconductor, using designer atomic nonmagnetic impurities and high-precision scanning tunneling microscopy (STM) at a base temperature of 30 mK. We detect 2 × 2 pair density modulations by Josephson STM with a superconducting tip and 2 × 2 pairing gap modulations by normal STM. We find that the pairing modulations in both cases are substantially suppressed upon doping the kagome lattice with dilute isovalent nonmagnetic impurities, whereas the charge order and uniform superconductivity remain robust. We further identify the correlation between atomic dopants and the local suppression of PDW. We attribute these findings to a nonmagnetic pair-breaking effect, arising from the phase modulation of PDW in the kagome d -orbital. Taken together with its signatures in other state-of-the-art spectroscopy and transport measurements linked by theory, our findings support the ground state of the kagome superconductor as a correlated topological phase with superconducting loop currents.

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Publication Details

Journal
Proceedings of the National Academy of Sciences
Published
2026-05-27
DOI
https://doi.org/10.1073/pnas.2604142123
Primary Topic
Topological Materials and Phenomena
Type
article
Field-Weighted Citation Impact
0.00

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article

Phase-sensitive evidence for pair density waves in a kagome superconductor

Xiquan Zheng, Hongyun Zhao, Matteo Dürrnagel, Hendrik Hohmann et al.
Proceedings of the National Academy of Sciences
Topological Materials and Phenomena
article

Phase-sensitive evidence for pair density waves in a kagome superconductor

Xiquan Zheng, Hongyun Zhao, Matteo Dürrnagel, Hendrik Hohmann, Kozo Okazaki, G Y Liu, Yigui Zhong, Q Wang, Junyi Zhang, Xiao-Yu Yan, Da Wang, Hailang Qin, X X Xu, Y Peng, Zhao Y, Hanbin Deng, Wei Song, Haiyang Ma, Muwei Gao, Xianxin Wu, Zhe Qu, Xiuhao Fan, Jia-Xin Yin, Ronny Thomale, Zurab Guguchia
article en

Abstract

Pair density wave (PDW) exhibits periodic amplitude and sign modulations of the superconducting order parameter. Such a pairing state has long been proposed to be highly sensitive to nonmagnetic scattering, but its experimental realization remains elusive. Here, we find a nonmagnetic PDW-breaking effect in a kagome superconductor, using designer atomic nonmagnetic impurities and high-precision scanning tunneling microscopy (STM) at a base temperature of 30 mK. We detect 2 × 2 pair density modulations by Josephson STM with a superconducting tip and 2 × 2 pairing gap modulations by normal STM. We find that the pairing modulations in both cases are substantially suppressed upon doping the kagome lattice with dilute isovalent nonmagnetic impurities, whereas the charge order and uniform superconductivity remain robust. We further identify the correlation between atomic dopants and the local suppression of PDW. We attribute these findings to a nonmagnetic pair-breaking effect, arising from the phase modulation of PDW in the kagome d -orbital. Taken together with its signatures in other state-of-the-art spectroscopy and transport measurements linked by theory, our findings support the ground state of the kagome superconductor as a correlated topological phase with superconducting loop currents.

Proceedings of the National Academy of SciencesVol. 123(22)
Johns Hopkins University (US), Peking University (CN), University of Würzburg (DE), Bay Institute (US), Hefei Institutes of Physical Science (CN), Johns Hopkins University Applied Physics Laboratory (US), ETH Zurich (CH), Institute for Solid State Physics and Optics (HU), Instituto de Física Teórica (ES), Institute of Theoretical Physics (CN), Quantum Technologies (Sweden) (SE), The University of Tokyo (JP), Nanjing University (CN)
National Natural Science Foundation of China, National Key Research and Development Program of China, Basic and Applied Basic Research Foundation of Guangdong Province
Openalex Percentile: Top 6%
Topological Materials and Phenomena
DOIOpen Access PDFOpenAlex
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