3-particle mechanism for pairing and superconductivity
I will present a new mechanism for superconductivity from strong electron-electron repulsion in multi-band systems. When the kinetic energy is small, the dynamics of nearby electrons on the lattice is strongly correlated. I will introduce a controlled expansion in the kinetic term to demonstrate pairing induced by correlated tunneling process involving a third electron in the occupied band. This mechanism can also be viewed as the real space picture of exciton-mediated pairing. Possible realization of this idea leading to strong-coupling, spin-triplet superconductivity in WTe2 and magic-angle graphene will be discussed.
Based on works with Valentine Crepel and Kevin Slagle:
 V. Crepel and L. Fu, arXiv:2012.08528
 V. Crepel and L. Fu, arXiv:2103.12060
 K. Slagle and L. Fu, Phys. Rev. B 102, 235423 (2020)