Abstract
Low-dimensional spin fluctuations play a crucial role in unconventional superconductors, with quasi-one-dimensional spin excitations potentially linked with spin-triplet superconductivity. The heavy fermion superconductor CeSb2 exhibits an unusual large inverted S-shaped upper critical field that suggests a possible triplet pairing state within its pressure-induced superconducting dome. Using inelastic neutron scattering, we discover quasi-one-dimensional magnetic excitations in CeSb2 emerging from nearly square Ce layers with minor orthorhombic deformation. We show that the data are well described by a ferromagnetic spin ladder model, where the "rungs"of the ladder straddle Ce bilayers. Moreover, we find that diffuse excitations akin to those in the ordered phase persist well above TN, suggesting that quasi-one-dimensional ferromagnetic paramagnons may significantly contribute to the unusual superconductivity that appears under pressure once magnetic order is suppressed.
| Original language | English |
|---|---|
| Article number | 116704 |
| Journal | Physical Review Letters |
| Volume | 134 |
| Issue number | 11 |
| DOIs | |
| State | Published - Mar 21 2025 |
Funding
This work was supported by the National Key R&D Program of China (Grants No. 2022YFA1402200, No. 2023YFA1406303, and No. 2024YFA1408303), the Key R&D Program of Zhejiang Province, China (Grant No. 2021C01002), the National Natural Science Foundation of China (Grants No. 12222410, No. 12174332, No. 12034017, No. 12374124, No. 12274363, and No. 12350710785), the Fundamental Research Funds for the Central Universities (Grant No. 226\u20132024\u201300068). Experiments at the ISIS Pulsed Neutron and Muon Source were supported by a beamtime allocation from the Science and Technology Facilities Council (RB2320153).