Salle S208 (LPS,2ème,aile Sud) + ONLINE (Zoom)


17 Mar 2023


11h00 - 12h00

I.PAUL: Pseudogap and Exceptional Van Hove Singularity in the Cuprates

	In the last few years there is increasing evidence that the behaviour of several cuprates in the doping range where the pseudogap ends is rather unusual. Thus, the charge response measured via electronic Raman spectroscopy shows anomalous enhancement, while the specific heat coefficient of the underlying metal increases in this doping range. Simultaneously, numerical studies of the Hubbard model have shown that the pseudogap exists only when the Fermi surface is hole-like, thereby raising the question why a strong coupling feature such as the pseudogap is sensitive to a weak coupling feature such as the Fermi surface topology.

I will present a phenomenological work that attempts to explain the above puzzling observations by postulating the presence of an “exceptional” van Hove singularity, which is a consequence of strong coupling physics, and which is not adiabatically connected to an ordinary weak-coupling van Hove singularity.