Effect of frustration on charge dynamics for a doped two-dimensional triangular Hubbard lattice: Comparison with a square lattice

TL;DR

This study investigates how geometrical frustration affects charge dynamics in a doped triangular Hubbard model, revealing weak charge-spin coupling but strong incoherent excitations due to frustration.

Contribution

It provides the first detailed comparison of charge dynamics between frustrated triangular and unfrustrated square lattices using exact diagonalization.

Findings

Charge degree of freedom is weakly coupled to spin in the triangular lattice.

Strong incoherent excitations extend to higher energies due to frustration.

Doping dependence of chemical potential and Drude weight differs from square lattice case.

Abstract

We examine the optical conductivity \sigma(\omega) and the chemical potential \mu, together with the spin correlation, in the strong-coupling limit of a hole-doped two-dimensional triangular Hubbard model near half filling by using an exact diagonalization technique. In contrast to the case of a square lattice without frustration, the doping dependences of \mu and the Drude weight indicate that the charge degree of freedom is weakly coupled to the spin degree of freedom. However, we find that \sigma(\omega) shows strong incoherent excitations extended to a higher energy region. This implies that geometrical frustration in strongly correlated electron systems influences incoherent charge dynamics.