Publication Details

Song, C., Wang, Y., Jiang, Y., Li, Z., Wang, L., He, K., Chen, X., Hoffman, J. E., Ma, X. & Xue, Q. (2014). Imaging the Electron-Boson Coupling in Superconducting FeSe Films Using a Scanning Tunneling Microscope. Physical Review Letters, 112 057002-1-057002-5.


Scanning tunneling spectroscopy has been used to reveal signatures of a bosonic mode in the local quasiparticle density of states of superconducting FeSe films. The mode appears below Tc as a "dip-hump" feature at energy Ω ∼ 4.7kBTc beyond the superconducting gap Δ. Spectra on strained regions of the FeSe films reveal simultaneous decreases in Δ and Ω. This contrasts with all previous reports on other high-Tc superconductors, where Δ locally anticorrelates with Ω. A local strong coupling model is found to reconcile the discrepancy well, and to provide a unified picture of the electron-boson coupling in unconventional superconductors.



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