Quantum vortex core and missing pseudogap in the multi-band BCS-BEC-crossover superconductor FeSe
ORAL
Abstract
The iron-based superconductor FeSe is considered to be in the BCS-BEC crossover regime where the superconducting gap is comparable to the Fermi energy. We performed spectroscopic-imaging scanning tunneling microscopy to search for spectroscopic signatures of the BCS-BEC crossover. The large superconducting-gap to Fermi-energy ratio may yield well separated discrete bound states in the vortex core, as well as a pseudogap above the superconducting transition temperature due to preformed Cooper pairs. We found a signature of the discrete vortex bound states but could not detect the pseudogap. We argue that these conflicting observations can be resolved if multi-band nature is taken into account.
*This work was supported by KAKENHI (Grant Nos. 15H02106, 15H05852, 16H04024, 18H01177, and 18H05227) and by the joint DFG-ANR Project (No.ER463/8-1) and DAAD PPP USA Grant No.N57316180.
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Presenters
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Tetsuo Hanaguri
- Center for Emergent Matter Science, RIKEN
- RIKEN CEMS