Direct observation of spin–orbit coupling in iron-based superconductors

By Sergey V. Borisenko, Danil V. Evtushinsky, I. Morozov, S. Wurmehl, B. Buchner, A. Yaresko, Timur K. Kim, M. Hoesch, Thomas Wolf, Nikolai Zhigadlo. Nature Physics, 2014

195 citations recorded by the source corpus.

A systematic spectroscopic analysis of the principal members of the iron pnictide family of superconductors reveals a substantial spin–orbit splitting. Spin–orbit coupling is a fundamental interaction in solids that can induce a broad range of unusual physical properties, from topologically non-trivial insulating states to unconventional pairing in superconductors1,2,3,4,5,6,7. In iron-based superconductors its role has, so far, not been considered of primary importance, with models based on spin- or orbital fluctuations pairing being used most widely8,9,10. Using angle-resolved photoemission spectroscopy, we directly observe a sizeable spin–orbit splitting in all the main members of the iron-based superconductors. We demonstrate that its impact on the low-energy electronic structure and details of the Fermi surface topology is stronger than that of possible nematic ordering11,12,13. The largest pairing gap is supported exactly by spin–orbit-coupling-induced Fermi surfaces, implying a direct relation between this interaction and the mechanism of high-temperature superconductivity.

Subfields: Condensed Matter Physics, Electronic, Optical and Magnetic Materials

View Paper: https://www.semanticscholar.org/paper/a35e2351a1072cb37368ca6c8a0b48471a5d3565