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Emergent spin-singlet pairing in the frustrated kagome metal Sc3Mn3Al7Si5

R. Guehne*, A. K. Sharma, P. Yanda†, J. Noky, J. Sichelschmidt, R. Koban, W. Schnelle, C. Shekhar, M. Baenitz et al.

C. Felser

  • *Contact author: robin.guehne@cpfs.mpg.de
  • †Contact author: Premakumar.Yanda@lmu.de
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Phys. Rev. B 113, 214430 – Published 10 June, 2026

DOI: https://doi.org/10.1103/8tjx-yy4w

Abstract

The metallic kagome compound Sc3Mn3Al7Si5 has attracted attention as a candidate platform where geometric frustration and itinerant electrons may cooperate to stabilize a quantum-disordered magnetic ground state. Here, we combine bulk thermodynamic probes, low-noise focused-ion-beam-device transport, and comprehensive Mn55 nuclear magnetic resonance (NMR) measurements to elucidate the low-temperature spin dynamics of this system. The bulk data reveal strongly reduced magnetic entropy, a negative magnetoresistance arising from spin scattering, and field-dependent transport indicates the spin fluctuations, while showing no signatures of long-range magnetic order. NMR provides a direct local view of the correlated Mn moments: the nuclear spin-spin relaxation time T2 exhibits a pronounced low-temperature enhancement driven by an indirect internuclear coupling through electronic spin fluctuations, whose temperature and distance dependencies point to partially gapped low-energy spin excitations. The spin-lattice relaxation rate T1−1 displays a broad peak near 10K that may originate from spin-singlet pairing and coincides with the resistivity crossover and a subtle heat-capacity anomaly. Together, our results suggest that Sc3Mn3Al7Si5 hosts an unconventional correlated state dominated by frustrated, gapped spin dynamics, placing it among the rare metallic kagome systems proximate to a quantum spin liquid.

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Phys. Rev. B 113, 214430– Published 10 June, 2026
  • Received 4 December 2025
  • Revised 17 March 2026
  • Accepted 12 May 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Open access publication funded by Max Planck Society.

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