Abstract
The tetragonal heavy-fermion superconductor CeRh2As2 (Tc=0.3 K) exhibits an exceptionally high critical field of 14 T for B∥c. It undergoes a field-driven first-order phase transition between superconducting states, potentially transitioning from spin-singlet to spin-triplet superconductivity. To further understand these superconducting states and the role of magnetism, we probe spin fluctuations in CeRh2As2 using neutron scattering. We find dynamic (π,π) antiferromagnetic (AFM) spin correlations with an anisotropic quasi-two-dimensional correlation volume. Our data place an upper limit of 0.31 μB on the staggered magnetization of corresponding Néel orders at T=0.08 K. Density functional theory calculations, treating Ce 4f electrons as core states, show that the AFM wave vector connects significant areas of the Fermi surface. Our findings indicate that the dominant excitations in CeRh2As2 for ℏω<1.2 meV are magnetic and suggest that superconductivity in CeRh2As2 is mediated by AFM spin fluctuations associated with a proximate quantum critical point.
| Original language | English |
|---|---|
| Article number | 266505 |
| Journal | Physical Review Letters |
| Volume | 133 |
| Issue number | 26 |
| DOIs | |
| State | Published - Dec 31 2024 |
Funding
We gratefully acknowledge the support from T. Xie and R. Kumar during the experiments and the valuable discussions with S.-H. Baek, P. Dai, Y. Liu, E. Hassinger, and D. Agterberg. Work at the Institute for Quantum Matter, was supported by DOE, Office of Science, Basic Energy Sciences under Award No. DE-SC0019331 and No. DE-SC0024469. Research at Washington University was supported by the National Science Foundation (NSF) Division of Materials Research Award No. DMR-2236528. Research at the University of Maryland was supported by the U.S. Department of Energy (DOE) Award No. DE-SC-0019154 (experimental preparation). J. P. acknowledges support from the Gordon and Betty Moore Foundation’s EPiQS Initiative through Grant No. GBMF4419. C. B. was supported by the Gordon and Betty Moore Foundation EPIQS program under GBMF9456 and acknowledges the hospitality of the Instituto de Física at UNAM, México. Research at Zhejiang University was supported by the National Key R&D Program of China (No. 2022YFA1402200). A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by ORNL.