Temperature-driven transition from the Wigner Crystal to the Bond-Charge-Density Wave in the Quasi-One-Dimensional Quarter-Filled band

Abstract

It is known that within the interacting electron model Hamiltonian for the one-dimensional 1/4-filled band, the singlet ground state is a Wigner crystal only if the nearest neighbor electron-electron repulsion is larger than a critical value. We show that this critical nearest neighbor Coulomb interaction is different for each spin subspace, with the critical value decreasing with increasing spin. As a consequence, with the lowering of temperature, there can occur a transition from a Wigner crystal charge-ordered state to a spin-Peierls state that is a Bond-Charge-Density Wave with charge occupancies different from the Wigner crystal. This transition is possible because spin excitations from the spin-Peierls state in the 1/4-filled band are necessarily accompanied by changes in site charge densities. We apply our theory to the 1/4-filled band quasi-one-dimensional organic charge-transfer solids in general and to 2:1 tetramethyltetrathiafulvalene (TMTTF) and tetramethyltetraselenafulvalene (TMTSF) cationic salts in particular. We believe that many recent experiments strongly indicate the Wigner crystal to Bond-Charge-Density Wave transition in several members of the TMTTF family. We explain the occurrence of two different antiferromagnetic phases but a single spin-Peierls state in the generic phase diagram for the 2:1 cationic solids. The antiferromagnetic phases can have either the Wigner crystal or the Bond-Charge-Spin-Density Wave charge occupancies. The spin-Peierls state is always a Bond-Charge-Density Wave.

12 pages, 8 EPS figures. Longer version of previous manuscript. Contains new numerical data as well as greatly expanded discussion

References in corpus (5)

• Theoretical Aspects of Charge Ordering in Molecular Conductors
• Strong electronic correlations in superconducting organic charge transfer salts
• Phase diagram of the one dimensional Hubbard-Holstein Model at 1/2 and 1/4 filling
• Coexistence of Charge Order and Spin-Peierls Lattice Distortion in One-Dimensional Organic Conductors
• Magnetic Phase Transition at 88 K in Na0.5CoO2 revealed by 23Na-NMR investigations

Cited by in corpus (6)

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• Spin and Charge Fluctuations and Lattice Effects on Charge Orders in α-(BEDT-TTF)_2I_3
• Phase competitions and coexistences in quasi-one-dimensional molecular conductors: exact diagonalization study
• Infrared Investigation of the Charge Ordering Pattern in the Organic Spin Ladder Candidate (DTTTF)2Cu(mnt)2
• Magnetism of one-dimensional Wigner lattices and its impact on charge order