Condensed Matter Seminar: Dr. Tonica Valla, Brookhaven National Laboratory


Location: 184 Nieuwland Science Hall (View on map )

High Tc Superconductivity in Cuprates: Endgame and New Beginnings

Dr. Tonica Valla
Physicist, Condensed Matter Physics & Materials Science
Brookhaven National Laboratory

More than three decades after the discovery and intense research, the mechanism of high-temperature superconductivity in cuprates remains unresolved. Here, I will present angle-resolved photoemission studies of Bi 2 Sr 2 CaCu 2 O 8+d single crystals cleaved and annealed in vacuum or in ozone to reduce or increase the doping. The in-situ annealing allows mapping of a wide doping regime, covering not only the superconducting dome, but also its endpoint on the overdoped side and the non-superconducting metallic phase. This has enabled us to study and correlate the changes in the electronic structure with onsets of different phenomena in the doping phase diagram, shedding a new light on their origins. We show that in the strongly overdoped regime, where superconductivity is the only remaining order, the detected mass renormalization that almost certainly reflects the pairing interaction, monotonically weakens with increasing doping and completely disappears precisely where superconductivity disappears. Our results indicate that superconductivity in this range is determined by the coupling strength and that the conventional phononic pairing mechanism can be definitely eliminated.

I will also discuss the problems and potential solutions in using the cuprates as a platform for topological superconductivity at the interfaces of topological matter and cuprate superconductors.

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