$μ$SR study of time-reversal symmetry constraints and bulk superfluid response in Li$_{0.95}$FeAs
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arXiv
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| Format: | Preprint |
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2026
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| _version_ | 1866915939451142144 |
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| author | Khasanov, Rustem Luetkens, Hubertus Zhigadlo, Nikolai D. |
| author_facet | Khasanov, Rustem Luetkens, Hubertus Zhigadlo, Nikolai D. |
| contents | We report zero-field (ZF) and transverse-field (TF) muon-spin rotation/relaxation ($μ$SR) measurements on superconducting Li$_{0.95}$FeAs ($T_{\rm c}\simeq16.0$ K) grown by a high-pressure self-flux method. The ZF-$μ$SR data show no detectable change of the electronic relaxation rate on cooling through $T_{\rm c}$, providing no evidence for time-reversal-symmetry breaking in the superconducting state. TF-$μ$SR measurements reveal a well-developed vortex response with strong flux pinning and a negligible nonsuperconducting contribution, confirming that superconductivity is a bulk property of the sample. From the second moment of the internal field distribution we determine a low-temperature in-plane magnetic penetration depth $λ_{ab}= 245(15)$ nm. The temperature dependence of the normalized superfluid density is well described by an effective two-gap model with $Δ_1 = 2.0(2)$ meV and $Δ_2 = 0.7(2)$ meV. A quantitative comparison with ARPES-based band weights shows that the $μ$SR response is dominated by the Fermi-surface sheets carrying the intermediate and small superconducting gaps, whereas the band hosting the largest gap contributes only about 3\% to the total superfluid density and is therefore not resolved in the present analysis. Taken together, these results establish Li$_{0.95}$FeAs as a bulk multigap superconductor without detectable time-reversal symmetry breaking and show how $μ$SR reconciles the gap scales reported by bulk and surface-sensitive probes in this multiband system. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2604_14376 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | $μ$SR study of time-reversal symmetry constraints and bulk superfluid response in Li$_{0.95}$FeAs Khasanov, Rustem Luetkens, Hubertus Zhigadlo, Nikolai D. Superconductivity We report zero-field (ZF) and transverse-field (TF) muon-spin rotation/relaxation ($μ$SR) measurements on superconducting Li$_{0.95}$FeAs ($T_{\rm c}\simeq16.0$ K) grown by a high-pressure self-flux method. The ZF-$μ$SR data show no detectable change of the electronic relaxation rate on cooling through $T_{\rm c}$, providing no evidence for time-reversal-symmetry breaking in the superconducting state. TF-$μ$SR measurements reveal a well-developed vortex response with strong flux pinning and a negligible nonsuperconducting contribution, confirming that superconductivity is a bulk property of the sample. From the second moment of the internal field distribution we determine a low-temperature in-plane magnetic penetration depth $λ_{ab}= 245(15)$ nm. The temperature dependence of the normalized superfluid density is well described by an effective two-gap model with $Δ_1 = 2.0(2)$ meV and $Δ_2 = 0.7(2)$ meV. A quantitative comparison with ARPES-based band weights shows that the $μ$SR response is dominated by the Fermi-surface sheets carrying the intermediate and small superconducting gaps, whereas the band hosting the largest gap contributes only about 3\% to the total superfluid density and is therefore not resolved in the present analysis. Taken together, these results establish Li$_{0.95}$FeAs as a bulk multigap superconductor without detectable time-reversal symmetry breaking and show how $μ$SR reconciles the gap scales reported by bulk and surface-sensitive probes in this multiband system. |
| title | $μ$SR study of time-reversal symmetry constraints and bulk superfluid response in Li$_{0.95}$FeAs |
| topic | Superconductivity |
| url | https://arxiv.org/abs/2604.14376 |