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Influence of Spin-Orbit Coupling in Iron-Based Superconductors.
R P Day1,2, G Levy1,2, M Michiardi1,2,3
1Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada.
Physical Review Letters
|September 1, 2018
Summary
Spin-orbit coupling significantly alters electronic structure in iron-based superconductors (LiFeAs, FeSe). This finding challenges current theories on superconductivity pairing mechanisms and the role of spin-orbit coupling.
Area of Science:
- Condensed Matter Physics
- Materials Science
Background:
- Iron-based superconductors exhibit complex electronic properties.
- Understanding the role of spin-orbit coupling (SOC) is crucial for elucidating their superconducting mechanisms.
Purpose of the Study:
- To investigate the influence of spin-orbit coupling on the electronic structure of iron-based superconductors.
- To determine the impact of SOC on superconducting gaps and pairing mechanisms.
Main Methods:
- Utilized circularly polarized spin and angle-resolved photoemission spectroscopy (SPARPES).
- Combined SPARPES with tight-binding calculations.
- Examined representative Fe-pnictides (LiFeAs) and Fe-chalcogenides (FeSe).
Main Results:
- Established ubiquitous modification of electronic structure by SOC in both Fe-pnictides and Fe-chalcogenides.
- Observed SOC's primary influence on low-energy hole pockets, correlating with larger superconducting gaps.
- Found SOC effects to be k_z dependent and comparable to orbital order energy scales in FeSe.
Conclusions:
- Spin-orbit coupling plays a significant, previously underestimated role in iron-based superconductors.
- Current models describing superconductivity solely by spin-singlet eigenstates may be incomplete.
- Further research is needed to explore novel pairing mechanisms and the precise role of SOC.
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