Modulation of charge-density waves by superlattice structures

TL;DR

This paper investigates how superlattice structures influence charge density waves in a one-dimensional Hubbard model, revealing their sensitivity to doping and potential for applications in heterostructures.

Contribution

It introduces a detailed analysis of CDW modulation in superlattice structures using DMRG, highlighting the impact of doping and effective Fermi wavevectors on CDW periods.

Findings

Charge density wave periods are predicted by effective Fermi wavevectors.

CDWs are highly sensitive to electron or hole doping.

Sharp 2k_F*-4k_F* transitions affect CDW behavior.

Abstract

We discuss the interplay between electronic correlations and an underlying superlattice structure in determining the period of charge density waves (CDW's), by considering a one-dimensional Hubbard model with a repeated (non-random) pattern of repulsive (U>0) and free (U=0) sites. Density matrix renormalization group diagonalization of finite systems (up to 120 sites) is used to calculate the charge-density correlation function and structure factor in the ground state. The modulation period can still be predicted through effective Fermi wavevectors, k_F*, and densities, and we have found that it is much more sensitive to electron (or hole) doping, both because of the narrow range of densities needed to go from q*=0 to \pi, but also due to sharp 2k_F*-4k_F* transitions; these features render CDW's more versatile for actual applications in heterostructures than in homogeneous systems.