Complex Quantum Systems/Condensed Matter Seminar

Ronny Thomale, Stanford University

"A Kohn Luttinger perspective on topological superconductivity"

3:30pm, RLM 5.104

Host: CQS

Abstract:

We argue that electron-driven pairing fluctuations, from the viewpoint of Fermi surface instabilities, generically provide a propensity towards topological superconductivity when the irreducible lattice representation associated with the Cooper pairs is multi-dimensional. For the square lattice, the px and py-type degenerate Cooper pairs yield p+ip triplet superconductivity, where we link its topological universality class to non-Abelian chiral spin liquid states recently introduced by us. In particular, in the case of water-intercalated cobaltates as well as graphene doped to van Hove filling, we illustrate this generation recipe for d+id topological singlet superconductivity on the triangular and honeycomb lattice. For the cobaltates, we can reconcile both the measured Knight shift data and excitation profile in the superconducting phase via an anisotropic d+id gap. For graphene, we predict a subtle competition between a spin density wave as well as d+id-wave and f-wave superconducting phases as a function of tight binding parameters, doping, and range of Coulomb interactions.