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TT: Fachverband Tiefe Temperaturen

TT 16: Superconductivity: Properties and Electronic Structure II

TT 16.10: Vortrag

Dienstag, 18. März 2025, 12:00–12:15, H32

Direct evidence of pairing up to the pseudogap energy in cuprate high-temperature superconductors — Jiasen Niu^1,2, Maialen Ortego Larrazabal³, Thomas Gozlinski^1,2, •Yudai Sato^1,2, Koen M. Bastiaans⁴, Tjerk Benschop¹, Jian-Feng Ge^1,5, Yaroslav M. Blanter⁴, Genda Gu⁶, Ingmar Swart³, and Milan P. Allan^1,2 — ¹Leiden Institute of Physics, Leiden University — ²Fakultät für Physik, Ludwig-Maximilians-Universität — ³Debye Institute of Nanomaterials Science — ⁴Kavli Institute of Nanoscience, Delft University of Technology — ⁵Max Planck Institute for Chemical Physics of Solids — ⁶Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory

In cuprate high-temperature superconductors, a pseudogap state is observed in a specific region of the phase diagram. Since it exists between the Mott insulating and superconducting phases, the origin of the peudogap is thought to be associated with electron pairing and/or a locally ordered state. Despite extensive studies, however, a definitive explanation remains elusive. Shot-noise experiments, which can directly detect electron pairing, hold the potential to resolve this long-standing debate. In this presentation, I will report on local shot-noise measurements on the unconventional superconductor Bi₂Sr₂Ca₂CuO_8+δ using scanning tunneling microscopy. We found that the pseudogap energy is associated with electron pairing, with pairing energies reaching up to 70 meV. Our results exclude the possibility of the pseudogap arising solely from local orders, and instead indicate a clear relation between the pseudogap state and Cooper pair formation.

Keywords: cuprate superconductors; pseudogap; scanning tunneling microscopy and spectroscopy; shot noise