Modulation of charge-density waves by superlattice structures

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 (nonrandom) 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 wave vectors kF* 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 π, but also due to sharp 2 kF* -4 kF* transitions; these features render CDW's more versatile for actual applications in heterostructures than in homogeneous systems. © 2006 The American Physical Society.