2017/07/13 by Guoyi Zhu, Zhu, Guo-Yi, Guang-Ming Zhang +1
Materials Science · Physics and Astronomy · #FOS: Physical sciences #Iron-based superconductors research #Physics of Superconductivity and Magnetism #Rare-earth and actinide compounds #Strongly Correlated Electrons (cond-mat.str-el) #Superconductivity (cond-mat.supr-con)
paper · pdf · doi:10.48550/arxiv.1707.04009
openalex publication_date 2017/07/13 · openalex created_date 2017/07/21 · openalex updated_date 2026/07/28
A plaquette-centered rotation symmetry C4p is identified to play a significant role in determining and stabilizing the Fermi-surface structure of Fe-based superconductors. Together with the S4 symmetry previously found, we are able to sort out the tangling orbitals and solve the puzzle of pairing symmetry of superconductivity in KFe2As2 in a simple but comprehensive way. By modeling the material with a strong coupling t-J1-J2 model, we find phase transitions of pairing symmetry driven by the competition between the local spin antiferromagnetic couplings from nodal dx2-y2× sx2+y2-wave to nodeless % sx2 y2 -wave through the intermediate s+id× s mixed pairing phase, which is consistent with the observation of pressure experiments. The emergent d-wave form factor inevitably arises from the projection of inter-orbital Cooper pairing onto the Fermi surface and is inherited from the electronic structure in the representation of C4p symmetry. Moreover, the S4 symmetry dictates 2 copies of d-wave pairing condensates, counting 8 nodes in total. We further show that weakly breaking C4p naturally leads to the octet nodal gap as precisely observed in laser angle resolved photoemission spectroscopy. The octet nodes reflect the collaboration of the C4p and S4 symmetries, which sheds new light on the enigma of the pairing symmetry in KFe2As2.