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SUMMARY:Strong Correlation and Unconventional Superconductivity in  Bulk a
 nd Trilayer Alkali-Doped Fullerides - Changming Yue (University of Fribour
 g)
DTSTART:20230601T130000Z
DTEND:20230601T140000Z
UID:TALK194920@talks.cam.ac.uk
CONTACT:Bo Peng
DESCRIPTION:The alkali-doped fullerides A3C60 (A = K\, Rb\, Cs) exhibit st
 rong correlation and unconventional superconductivity (SC) in both bulk an
 d thin films. In the first part of the seminar [1]\, the speaker will inve
 stigate the unconventional pairing mechanism in bulk A3C60 using dynamical
  mean-field theory (DMFT) in the Nambu formalism. He will show that the lo
 cal orbital fluctuations are substantially enhanced in the superconducting
  state and provide the pairing glue in A3C60. A lock-in phenomenon between
  the SC gap (fermionic) and the local orbital fluctuation energy (bosonic)
  is found\, which is consistent with an experimentally observed universal 
 linear relationship. \n\nEpitaxially grown K3+xC60 thin films exhibit a Mo
 tt insulating state in the monolayer and a strong electron-hole doping asy
 mmetry in the superconducting state in the trilayer [2]\, which asymmetry 
 is absent in the three-dimensional bulk limit. In the second part of the s
 eminar [3]\, using DFT+DMFT\, the speaker will show that this doping asymm
 etry results from a substantial charge reshuffling from the top layer to t
 he middle layer. The interlayer charge transfer and layer-selective metal-
 insulator transition result from the interplay between crystal field split
 tings\, strong Coulomb interactions\, and an effectively negative Hund cou
 pling. \n\nIf time is allowed\, the speaker would like to report our recen
 t progress in the analytic continuation of anomalous self-energy and its a
 pplication in K3C60\, which paves the way for the theoretical study of mom
 entum resolved spectra in the SC phase using quantum Monte-Carlo method [4
 ]. \n\n\n[1] C. Yue\, S. Hoshino\, A. Koga and P. Werner\, Phys. Rev. B 10
 4\, 075107 (2021)\n\n[2] Ming-qiang Ren\, et. al.\, Phys. Rev. Lett. 124\,
  187001 (2020)\n\n[3] C. Yue\, Y. Nomura\, and P. Werner\, Phys. Rev. Lett
 . 129\, 066403 (2022)\n\n[4] C. Yue. And P. Werner\, arXiv: 2303.16888 (20
 23)
LOCATION:Zoom
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