Abstract
ACo2Se2 (A=K, Rb, Cs) is a homologue of the iron-based superconductor AFe2Se2. From a comprehensive study of RbCo2Se2 via measurements of magnetization, transport, neutron diffraction, angle-resolved photoemission spectroscopy, and first-principles calculations, we identify a ferromagnetic order accompanied by an orbital-dependent spin splitting of the electronic dispersions. Furthermore, we identify the ordered moment to be dominated by a dx2-y2 flat band near the Fermi level, which exhibits the largest spin splitting across the ferromagnetic transition, suggesting an itinerant origin of the ferromagnetism. In the broader context of the iron-based superconductors, we find this dx2-y2 flat band to be a common feature in the band structures of both iron chalcogenides and iron pnictides, accessible via heavy electron doping.
| Original language | English |
|---|---|
| Article number | 165105 |
| Journal | Physical Review B |
| Volume | 103 |
| Issue number | 16 |
| DOIs | |
| State | Published - Apr 5 2021 |
Funding
This research used resources of the Advanced Light Source, a U.S. DOE Office of Science User Facility under Contract No. DE-AC02-05CH11231, and the High Flux Isotope Reactor, a DOE Office of Science User Facility operated by Oak Ridge National Laboratory. The work at Lawrence Berkeley National Laboratory was funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division under Contract No. DE-AC02-05-CH11231 (Quantum Materials Program KC2202). The work at Rice University was supported by Robert A. Welch Foundation Grant No. C-2024 as well as the Alfred P. Sloan Foundation Grant No. FG-2019-12224. Work at Sun Yat-Sen University was supported by the National Natural Science Foundation of China (Grant No. 11904414), Natural Science Foundation of Guangdong (Grant No. 2018A030313055), National Key Research and Development Program of China (Grant No. 2019YFA0705702), and Young Zhujiang Scholar Program. A.F.K. acknowledges support by the National Science Foundation under Grant No. DMR-1752713.