05 March 2024

Webinar DMONS presented by M. Benjamin Bacq-Labreuil

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

Benjamin BACQ-LABREUIL (Institut Quantique de l’Université de Sherbrooke – Canada)

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. We trace back the miscroscopic origin of these observations to the existence of interstitial conduction states confined between the CuO2 layers which favor the inner planes. Our work paves the way towards ab initio material-specific predictions of the superconducting order parameter.

Contact : Mébarek ALOUANI : mebarek.alouani@ipcms.unistra.fr

Connexion links on March 5th, 2024  from 14h50 :

https://cnrs.zoom.us/j/94911816568?pwd=c0JoY2EyU1VJOG5SN2NsQXNDRG81Zz09
Meeting ID: 949 1181 6568
Secret code: 0FaFbn

05 March 2024, 15h0016h00
By visioconference

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