Dresden 2017 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 70: Superconductivity: Fe-based Superconductors - Theory
TT 70.7: Vortrag
Donnerstag, 23. März 2017, 17:00–17:15, HSZ 103
Interfacial electron-phonon coupling strength and high-Tc superconductivity in monolayer FeSe/SrTiO3 — •Alex Aperis and Peter M. Oppeneer — Uppsala University, Sweden
Superconductivity in monolayer FeSe on SrTiO3 reaches mysteriously high transition temperatures of typically 50-70 K and up to 100 K, much higher than the Tc=8 K of bulk FeSe. At the FeSe/SrTiO3 interface, a coupling between SrTiO3 phonons and FeSe electrons that manifests as electron replica bands, is commonly believed to enhance Tc moderately but not enough to fully explain it. Here, we employ fully anisotropic, full bandwidth multiband Eliashberg calculations to examine the impact of these phonons on the superconducting state of FeSe/SrTiO3. We find that the interfacial electron-phonon interaction which is hidden behind the seemingly weak coupling constant, λm=0.4, fully accounts for the high-Tc while also solving puzzling experimental facts like the s-wave symmetry and replica bands. Our calculations indicate that replica band formation has a Tc-decreasing effect which is nevertheless overcompensated by Tc-enhancing Cooper pairing at bands away from the Fermi level. We predict this mechanism to produce a strong coupling dip-hump signature in the tunnelling spectra.