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- Title
Pseudospin-triplet pairing in iron-chalcogenide superconductors.
- Authors
Zeng, Meng; Xu, Dong-Hui; Wang, Zi-Ming; Hu, Lun-Hui; Zhang, Fu-Chun
- Abstract
Understanding the pairing symmetry is a crucial theoretical aspect in the study of unconventional superconductivity for interpreting experimental results. Here we study superconductivity of electron systems with both spin and pseudospin-1/2 degrees of freedom. By solving linearized gap equations, we derive a weak coupling criterion for the even-parity spin-singlet pseudospin-triplet pairing. It can generally mix with the on-site s-wave pairing since both of them belong to the same symmetry representation (A1g) and their mixture could naturally give rise to anisotropic intra-band pairing gap functions with or without nodes. This may directly explain why some of the iron-chalcogenide superconductors are fully gapped (e.g. FeSe thin film) and some have nodes (e.g. LaFePO and LiFeP). We also find that the anisotropy of gap functions can be enhanced when the principal rotation symmetry is spontaneously broken in the normal state such as nematicity, and the energetic stabilization of pseudospin-triplet pairings indicates the coexistence of nematicity and superconductivity. This could be potentially applied to bulk FeSe, where gap anisotropy has been experimentally observed. The underlying symmetry of a given system dictates the material properties from the electronic band structure to its spontaneous symmetry broken ordering. Here, the authors consider the effects of symmetry breaking and investigate spin-singlet orbital triplet pairings in unconventional superconductors with electronic nematicity, they apply their results to iron-based superconductors and twisted bilayer graphene.
- Subjects
IRON-based superconductors; SUPERCONDUCTORS; ELECTRONIC band structure; DEGREES of freedom; THIN films; SUPERCONDUCTIVITY
- Publication
Communications Physics, 2024, Vol 7, Issue 1, p1
- ISSN
2399-3650
- Publication type
Article
- DOI
10.1038/s42005-023-01495-4