Coexistence of Charge Order and Spin-Peierls Lattice Distortion in One-Dimensional Organic Conductors

TL;DR

This paper investigates the coexistence of charge order and spin-Peierls lattice distortion in one-dimensional organic conductors, revealing how strong correlations stabilize charge-ordered states alongside lattice distortions.

Contribution

It provides a combined analytical and numerical study of the extended Peierls-Hubbard model, identifying conditions for coexistence of charge order and spin-Peierls states.

Findings

Charge order is stabilized with large Coulomb interactions.

Two competing spin-Peierls states are identified.

Numerical DMRG confirms the dominance of charge order in certain regimes.

Abstract

The electronic properties of quarter-filled organic materials showing spin-Peierls transition are investigated theoretically. By studying the one-dimensional extended Peierls-Hubbard model analytically as well as numerically, we find that there is a competition between two different spin-Peierls states due to the tetramized lattice distortion in the strongly correlated regime. One is accompanied by lattice dimerization which can be interpreted as a spontaneous Mott insulator, while the other shows the existence of charge order of Wigner crystal-type. Results of numerical density matrix renormalization group computations on sufficiently large system sizes show that the latter is stabilized in the ground state when both the on-site and the inter-site Coulomb interactions are large.