Drude weight and total optical weight in a t-t'-J model

TL;DR

This paper investigates how the Drude weight and optical spectral weight evolve with doping in a t-t'-J model, revealing linear increases near half-filling and saturation at higher doping, aligning with experimental observations.

Contribution

It provides a quantum-fluctuation-inclusive analysis of optical weights in a t-t'-J model, elucidating their doping dependence near the Mott transition.

Findings

D and K increase linearly with small hole doping

D and K saturate and decrease at higher doping levels

Results qualitatively match optical conductivity experiments in doped antiferromagnets

Abstract

We study the Drude weight D and the total optical weight K for a t-t'-J model on a square lattice that exhibits a metallic phase-modulated antiferromagnetic ground state close to half-filling. Within a suitable 1/N expansion that includes leading quantum-fluctuation effects, D and K are found to increase linearly with small hole doping away from the Mott metal-insulator transition point at half-filling. The slow zero-sound velocity near the latter transition identifies with the velocity of the lower-energy branch of the twofold excitation spectrum. At higher doping values, D and K eventually saturate and then start to decrease. These features are in qualitative agreement with optical conductivity measurements in doped antiferromagnets.