“Models for unconventional superconductors; from high Tc to moiré”
Unconventional superconductors have appeared in a variety of contexts where strong electronic correlations are present, with two notable examples being the cuprate superconductors and moiré materials. In the first part of my talk, I will discuss several examples of superconductivity appearing in stacked Van der Waals structures, and possible mechanisms, with a focus on fluctuations of a time-reversal symmetric intervalley coherent order. In the case of twisted bilayer graphene, I will show the leading instability is an s-wave inter-band pairing state with non-trivial spectral properties. In the more recent example of twisted bilayer WSe2, we will find competition between 3 nodal representations, and discuss the implications of band topology on pairing.
In the second part of my talk, I will focus on the cuprate superconductors and present a theory of d-wave superconductivity and charge order as a confining instabilities of the so-called π-flux spin liquid, and explore the implications of a confinement transition on experimental observables in the superconducting phase. I will also discuss the 1/N corrections to our theory and predictions on spectral properties in the ordered phases.
Host: Meng Cheng