Signature of magnetoelectric coupling driven finite momentum pairing in 3D ising superconductor.
basic_science · Level V
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- Record sourced from PubMed, PMID 40681507.
- Also identified by DOI 10.1038/s41467-025-61882-z and PMC identifier 12274449.
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Abstract
The finite momentum superconducting paring states (FMPs) represent a forefront of condensed matter physics. Here we report experimental evidence of FMP in a locally noncentrosymmetric bulk superconductor 4H<sub>b</sub>-TaS<sub>2</sub>. Using hard X-ray diffraction and angle-resolved photoemission spectroscopy, we reveal unusual 2D ferro-rotational charge density wave (CDW) and weak interlayer hopping in 4H<sub>b</sub>-TaS<sub>2</sub>. The superconducting upper critical field, H<sub>c2</sub>, linearly increases via decreasing temperature, and well exceeds the Pauli limit, suggesting the dominant orbital pair-breaking mechanism. Remarkably, we observed evidence of field-induced superconductivity-to-superconductivity transition that breaks continuous rotational symmetry of the s-wave uniform pairing in the Bardeen-Cooper-Schrieffer theory down to the six-fold rotation symmetry. Ginzburg-Landau free energy analysis shows that magnetoelectric coupling, induced by 2D ferro-rotational CDW, stabilizes FMP that provides an explanation of the lowering rotation symmetry. Our results provide a new understanding of unconventional superconducting behaviors of the bulk quantum heterostructure 4H<sub>b</sub>-TaS<sub>2</sub>.