Symmetry-broken Kondo screening and zero-energy mode in a kagome superconductor

Nature Physics (2026)Cite this article Quantum states of matter reorganize themselves in response to defects, giving rise to emergent local excitations that reflect the intrinsic properties of the underlying phases. Magnetic impurities, for example, generate Kondo screening in a Fermi liquid and Yu–Shiba–Rusinov states in a conventional superconductor. Yet, it remains unclear whether such impurities can trigger unconventional phenomena in the kagome superconductor AV3Sb5, where A represents K, Rb or Cs, which hosts a putative loop current order intertwined with its charge density wave. Here we demonstrate the emergence of Kondo resonance states near magnetic dopants in CsV3Sb5. Using scanning tunnelling microscopy, we find that the spatial structure of the Kondo screening near magnetic Cr impurities breaks all in-plane mirror symmetries of the kagome lattice. This symmetry breaking suggests the presence of an underlying electronic chirality arising from the proposed orbital loop current order. We also observe a pronounced zero-bias conductance peak arising from weakly magnetic V vacancies. These results provide insight into the coexistence and interplay of quantum states in kagome lattice compounds.This is a preview of subscription content, access via your institution Access Nature and 54 other Nature Portfolio journals Get Nature+, our best-value online-access subscription $32.99 / 30 days cancel any timeSubscribe to this journal Receive 12 print issues and online access $259.00 per yearonly $21.58 per issueBuy this articleUSD 39.95Prices may be subject to local taxes which are calculated during checkoutThe data supporting the findings of this study are available at https://doi.org/10.57760/sciencedb.36785. Additional data are available from the corresponding author upon reasonable request. 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Lett. 50, 1998 (1983).Article ADS Google Scholar Download referencesThis work was supported by the National Key R&D Program of China (grant nos. 2022YFA1403200 (N.H., W.L. and X.H.), 2024YFA1611103 (L.S.), and 2024YFA1613200 (N.H.)), acknowledge support from the Innovation Program for Quantum Science and Technology (grant no. 2021ZD0302802 (Zhenyu Wang, X.C. and L.S.)), the National Natural Science Foundation of China (grant nos. 12474128 (L.S.), 92265104 (N.H.), 52261135638 (Zhenyu Wang), 12204008 (Y.T.), 12104004 (Z. Zhang), 12304162 (T.H.), 12374133 (X.H.) and 12022413 (N.H.)), the Scientific Research Innovation Capability Support Project for Young Faculty (grant no. ZYGXQNJSKYCXNLZCXM-M25 (Zhenyu Wang)), the Basic Research Program of the Chinese Academy of Sciences Based on Major Scientific Infrastructures (grant no. JZHKYPT-2021-08 (N.H., Zhenyu Wang and X.C.)), and the Anhui Provincial Major S&T Project (s202305a12020005 (N.H.)). We are grateful for the assistance of the Steady High Magnetic Field Facilities of the High Magnetic Field Laboratory (CAS) for providing technical support and assistance in data collection and analysis.These authors contributed equally: Yubing Tu, Zongyuan Zhang, Wenjian Lu, Yuhang Xiao.State Key Laboratory of Opto-Electronic Information Acquisition and Protection Technology, Institutes of Physical Science and Information Technology, Anhui University, Hefei, ChinaYubing Tu, Zongyuan Zhang, Tao Han, Zekun Zhou, Xingyuan Hou & Lei ShanLeibniz International Joint Research Center of Materials Sciences of Anhui Province, Anhui University, Hefei, ChinaYubing Tu, Zongyuan Zhang, Tao Han, Xingyuan Hou & Lei ShanCenter of Free Electron Laser and High Magnetic Field, Anhui University, Hefei, ChinaZongyuan Zhang, Xingyuan Hou & Lei ShanKey Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei, ChinaWenjian Lu & Run LvAnhui Provincial Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, ChinaYuhang Xiao & Ning HaoDepartment of Physics, University of Science and Technology of China, Hefei, ChinaZhuying Wang, Zhenyu Wang & Xianhui ChenHefei National Laboratory, University of Science and Technology of China, Hefei, ChinaZhenyu Wang, Xianhui Chen & Lei ShanSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarL.S. designed the experiments. L.S., Zhenyu Wang and N.H. supervised the project. Y.T., Z. Zhang and Zhuying Wang performed the STM experiments and data analysis with guidance from L.S. and Zhenyu Wang. T.H. and Z. Zhou prepared and characterized the samples. W.L., R.L.,Y.X. and N.H. carried out the theoretical calculations. L.S., N.H., X.H., Zhenyu Wang and X.C. interpreted the results and wrote the manuscript. All of the authors discussed the experimental data and commented on the manuscript.Correspondence to Ning Hao, Zhenyu Wang or Lei Shan.The authors declare no competing interests.Nature Physics thanks Antonio Seridonio and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.a, c, Typical STM topographies of CsV2.925Ta0.075Sb5 and CsV2.997Cr0.003Sb5. The bright protrusions represent Ta or Cr atoms that substitute for the V atoms in the underlying kagome layer. b, d, Distributions of dopant atoms in the field of view shown in a and c. The numbers of Ta and Cr atoms, determined by counting, are 646 and 18, respectively. e-i, Five types of native defects in addition to Cr (Ta) dopants, marked with color-coded boxes in c. The STM setup conditions: Vs = +1.5 V, It = 300 pA (a); Vs = +1.5 V, It = 100 pA (c); Vs = −70 mV, It = 200 pA (e-i).a, b, STM topographies acquired in the same area of a pristine sample with different scanning bias voltages. c-e, Atomically resolved STM topographies of the Sb1 vacancy (c), Sb2 vacancy (d) and Sb2 defect (e), as indicated by the arrows in a and b. f, Spectra taken on top of and away from the Sb1 vacancy, Sb2 vacancy and Sb2 defect. The STM setup conditions: Vs = +80 mV It = 500 pA (a); Vs = −80 mV It = 500 pA (b); Vs = +80 mV It = 300 pA (c); Vs = +80 mV It = 200 pA (d); Vs = +80 mV It = 200 pA (e); Vs = −5 mV, It = 300 pA, Vm = 0.05 mV, T = 0.4 K (f).Source dataa-c, STM topographies of the three Cr dopants. d-f, dI/dV map for the Cr dopants shown in a to c. The yellow dots indicate the atomic locations of the Cr dopants. g-i, dI/dV spectra taken at the positions showing the strongest Kondo resonance. STM setup conditions: Vs = −500 mV, It = 100 pA (a); Vs = −80 mV, It = 40 pA (b); Vs = +80 mV, It = 20 pA (c); Vs = −5 mV, It = 300 pA, Vm = 0.05 mV, T = 0.4 K (g); Vs = −20 mV, It = 300 pA, Vm = 0.2 mV, T = 1.5 K (h); Vs = −20 mV, It = 300 pA, Vm = 0.2 mV, T = 1.5 K (i).Source dataa, dI/dV map showing the spatial distribution of the Kondo resonance. b-d, dI/dV spectra measured at different temperatures at the red dot shown in a. The solid curves represent the thermally convolved Fano (b), Frota (c) and Hurwitz fits (d). e, Temperature dependence of the HWHM extracted from the fits in b to d. The solid lines in b-d represent the fits to the empirical expression of \({HWHM}=1/2\sqrt{{(\alpha {k}_{B}{T}_{{eff}})}^{2}+{(2{k}_{B}{T}_{K})}^{2}}\).Source dataa, STM topography and dI/dV mappings of two nearby Cr dopants. b-d, STM topographies and dI/dV maps of three individual Cr dopants on the same surface. The orange dotted lines indicate the direction of the unidirectional 4a0 order, and the orange arrows indicate the spatial patterns of the Kondo screening. STM setup conditions: Vs = −80 mV, It = 50 pA (a); Vs = −80 mV, It = 1 nA (b); Vs = −85 mV, It = 1 nA (c); Vs = −80 mV, It = 50 pA (d).a, b, Real-space CDW pattern (a) and the loop current order (b) considered in our simulation. c-f, Local modulation of the charge density near a magnetic impurity (marked by red arrows) with different mean-field orders. The chirality of the dI/dV pattern (with the loop current order) is indicated by the red circle in e. The parameter settings are as follows: \({\rm{t}}=1\,\)(real hopping parameter), \(\eta =-0.3\) (imaginary hopping parameter), \({\rm{\lambda }}=0.015\) (CDW order parameter), \({\rm{\mu }}=0.23\) (chemical potential), \({\rm{\omega }}=0.02\) (probe energy), \({\Gamma }_{{\rm{K}}}\) = 0.4, \({\varepsilon }_{{\rm{K}}}\) = 0.02, \({{\rm{Z}}}_{{\rm{K}}}=0.2\), and \({{\rm{U}}}_{1}=1\). The lattice size is taken as 10×10 in units of the 2×2 reconstructed cell to simulate the small Fermi surface. Note that to compensate the quite large energy spacing between the discrete energy spectra, we adopt a larger broadening of \({\Gamma }_{{\rm{K}}}\).a, b, Spectra taken at a V vacancy in a pristine sample with different vertical magnetic fields. c, d, Spectra taken at another V vacancy at different temperatures. STM setup conditions: Vs = −80 mV, It = 20 pA (a); Vs = −5 mV, It = 300 pA, Vm = 0.05 mV, T = 0.4 K (b); Vs = −80 mV, It = 20 pA (c); Vs = −5 mV, It = 300 pA, Vm = 0.05 mV, B = 0 T (d).Source dataSupplementary Table 1, Sections 1–7 and Figs. 1–9.STS data on impurities.Kondo resonance peak.Zero-energy state and its evolution.Coexisting zero-energy state and YSR states.STS data near native Sb-site defects.More Kondo resonance state data.Temperature-dependent Kondo resonance.Magnetic-field- and temperature-dependent zero-energy conductance peak.Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.Reprints and permissionsTu, Y., Zhang, Z., Lu, W. et al. Symmetry-broken Kondo screening and zero-energy mode in a kagome superconductor. Nat. Phys. (2026). https://doi.org/10.1038/s41567-026-03223-5Download citationReceived: 13 March 2025Accepted: 20 February 2026Published: 24 March 2026Version of record: 24 March 2026DOI: https://doi.org/10.1038/s41567-026-03223-5Anyone you share the following link with will be able to read this content:Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative