Events

Next Quantum Materials Seminar/LANEF:

Thursday, January 11th 2024 at 2:00 pm

Benjamin Bacq  (Institut Quantique, Sherbrooke University)

“ Towards predictive ab initio methods for unconventional superconductivity: a study of multilayer cuprates “

To access this seminar:

Institut Néel CNRS, Building K, Room Rémy Lemaire  (K223)

Abstract: High-temperature n-layer cuprate superconductors have the remarkable universal feature that the maximum transition temperature TC is always obtained for the tri-layer compound. It remains unclear how the recent breakthroughs, highlighting the relation of the charge transfer gap (CTG) and the spin-exchange J with the pairing density, can be related to this universality. By integrating an exact diagonalization solver to a density functional theory (DFT) plus cluster dynamical mean-field theory (CDMFT) framework, we were able to carry charge self-consistent DFT+CDMFT calculations for n=1-5 multilayer cuprates. Remarkably, the undoped compounds already host a peculiar behavior as a function of n: the CTG first decreases until reaching a minimum at n=3, and then stabilizes. The CTG is smaller in the inner CuO2 planes, and consequently the spin exchange J is larger as compared to the outer planes, which corroborates the experimental evidence of stronger antiferromagnetic spin fluctuations in the inner planes. Upon hole-doping, the charge carriers are inhomogeneously distributed among the different CuO2 planes, which leads to the coexistence of Fermi pockets and arcs in the Fermi surface as observed in experiments. Our work paves the way towards ab initio material-specific predictions of the superconducting order parameter

The organizers:

Elsa Lhotel (elsa.lhotel@neel.cnrs.fr)
Florence Levy-Bertrand (florence.levy-bertrand@neel.cnrs.fr)