|December 8||Dr. Shang-Shun Zhang (University of Tennessee)||Paring from strong repulsion in triangular lattice Hubbard model|
Dr. Shang-Shun Zhang (University of Tennessee)
Paring from strong repulsion in triangular lattice Hubbard model
The generation of an effective attraction between electrons out of the bare Coulomb repulsion is a long sought-after goal of the condensed matter community. In this talk I will describe a paring mechanism between holes in the dilute limit of doped frustrated Mott insulators. We will see that magnons provide a strong glue in the infinitely repulsive limit of triangular lattice Hubbard model. The strongly attractive hole-magnon interaction is a manifestation of a “counter-Nagaoka” theorem: the single-hole kinetic energy is minimized for an antiferromagnetically ordered state. We will show that the resulting hole-magnon glue is strong enough to bind a second hole and form a hole-hole-magnon three-body bound state. Remarkably, the binding energy of this “composite Cooper pair” is rather strong, while its effective mass still has a moderate value, giving rise to relatively high transition temperature for superconductivity. We will discuss possible experimental realizations of this new mechanism.