Fermions and bosons : excitons in strongly correlated materials

Abstract

This thesis involves excitonic physics in

bilayers of strongly correlated electron materials. The fermionic

bilayer extended Hubbard model is studied by means of mean field theory

and Determinant Quantum Monte Carlo simulations. A bosonic low-energy effective theory is developed, called the exciton t-J model. The phase diagram and the elementary excitations of this model are investigated. Surprisingly, the excitons are predicted to exhibit Ising confinement physics in the antiferromagnetic phase. In the exciton superfluid phase the magnetic triplon modes borrow kinetic energy from the excitons.