MatQ:

https://umontreal.zoom.us/j/93026432919?pwd=SkVyQ2w2Z3Q2SW5CcjJQa2QwVlRsZz09

Meeting ID: 930 2643 2919

Password: 137

 Jacques Lengaigne 

Affiliation:

Département de génie mécanique,École de technologie supérieure jacques.lengaigne.1@ens.etsmtl.ca

Titre:

Masques et filtration, lesmembranes qui font le travail

Masks and filtration, themembranes that do the trick

Résumé:

Le masque, toujours dans notreface, littéralement... Comment cette technologie d’apparence si anodines’est-elle imposée dans notre vie de tous les jours? Dans cette courteconversation, je vais tenter de vous présenter la vie intime du masque: desmécanismes de filtration aux défis de la fabrication auxquels nous faisons facepour approvisionner le monde. Sans conspiration, presque pas de politique,surtout de l’ingénierie, une pincée de science, venez pour une trempette dansla mare des textiles de commodités.

Abstract:

The ubiquitous mask, always inour face, literally... How does this seemingly simple piece of technology hassecured a place in our everyday life? In this short talk, I will present theinner life of the mask: from the simple working principles of filtration to themanufacturing hurdles we face to supply the world. No conspiracy, minimalpolitics, mostly engineering, a touch of science, come for a dive in the worldof commodity textiles.

 Sidhartha Dash

 Title: "Oxygen hole doping and superconductivity in the three-band Hubbard model"

Abstract:  
The one-band Hubbard model describes quite well various aspects of the cuprate superconductors. However, it does not take into account the oxygen orbitals explicitly and hence cannot explain the experimental observations related to oxygen hole doping. For instance, Rybicki et al. [1] have shown that the superconducting critical temperature (T_c) is correlated with the hole content on the oxygen orbitals. In this talk, I will present our recent work on the three-band Hubbard model, which is a more accurate model for cuprates, using cluster dynamical mean field theory (CDMFT) at zero temperature with exact diagonalization (ED) impurity solver. We start with realistic values of band parameters from Weber et al. [2] and explore different parameter-sets. We observe that the superconducting order parameter at optimal doping is monotonously related to the corresponding oxygen hole doping and the charge-transfer gap, in the parameter regime relevant to cuprates. We also show indications that pairing in the three-band model is mediated by short-range antiferromagnetic interactions as is also known for the one-band Hubbard model.
1.    Rybicki, Damian, et al. "Perspective on the phase diagram of cuprate high-temperature superconductors." Nature communications 7.1 (2016): 1-6.

2.    Weber, Cédric, et al. "Scaling of the transition temperature of hole-doped cuprate superconductors with the charge-transfer energy." EPL (Europhysics Letters) 100.3 (2012): 37001.