Regensburg 2025 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 37: Correlated Electrons: Poster
TT 37.34: Poster
Mittwoch, 19. März 2025, 15:00–18:00, P4
Feshbach resonance in a strongly repulsive ladder of mixed dimensionality: a possible scenario for bilayer nickelate superconductors — •Hannah Lange1,2,3, Lukas Homeier1,3, Eugene Demler4, Fabian Grusdt1,3, and Annabelle Bohrdt3,5 — 1LMU Munich — 2Max-Planck-Institute for Quantum Optics, Garching — 3Munich Center for QST, Munich — 4ETH Zurich — 5University of Regensburg
Since the discovery of superconductivity in cuprate materials, the minimal ingredients for high-Tc superconductivity have been an outstanding puzzle. Motivated by the recently discovered nickelate bilayer superconductor LNO under pressure, we study a minimal bilayer model, in which, as in LNO, inter- and intralayer magnetic interactions but no interlayer hopping are present: a mixed-dimensional (mixD) t-J model. The single and coupled mixD ladders we study feature a crossover from tightly bound pairs of holes (closed channel) at small repulsion, to more spatially extended, correlated pairs of individual holes (open channel) at large repulsion. We derive an effective model for the latter, in which the attraction is mediated by the closed channel, in analogy to atomic Feshbach resonances. Using density matrix renormalization group (DMRG) simulations we reveal a dome of large binding energies at around 30% doping, accompanied by a change of the Fermi surface volume. Our work provides a microscopic theory of pairing in the doped mixD system with dominant repulsion and our predictions can be tested in state-of-the-art quantum simulators.
Keywords: Feshbach resonance; LNO; mixed dimensional system; unconventional superconductivity