Details

Autor(en) / Beteiligte

• Valenzuela, B.
• Fratini, S.
• Baeriswyl, D.

Titel

Charge and spin order in one-dimensional electron systems with long-range Coulomb interactions

Ist Teil von

• Physical review. B, Condensed matter, 2003-07, Vol.68 (4), Article 045112

Ort / Verlag

American Physical Society

Erscheinungsjahr

2003

Link zum Volltext

Quelle

APS Digital Backfile Archive (DFG Nationallizenzen)

Beschreibungen/Notizen

• We study a system of electrons interacting through long--range Coulomb forces on a one--dimensional lattice, by means of a variational ansatz which is the strong--coupling counterpart of the Gutzwiller wave function. Our aim is to describe the quantum analogue of Hubbard\'s classical ``generalized Wigner crystal\'\'. We first analyse charge ordering in a system of spinless fermions, with particular attention to the effects of lattice commensurability. We argue that for a general (rational) number of electrons per site $n$ there are three regimes, depending on the relative strength $V$ of the long--range Coulomb interaction (as compared to the hopping amplitude $t$). For very large $V$ the quantum ground state differs little from Hubbard\'s classical solution, for intermediate to large values of $V$ we recover essentially the Wigner crystal of the continuum model, and for small $V$ the charge modulation amounts to a small--amplitude charge--density wave. We then include the spin degrees of freedom and show that in the Wigner crystal regimes (i.e. for large $V$) they are coupled by an antiferromagnetic kinetic exchange $J$, which turns out to be smaller than the energy scale governing the charge degrees of freedom. Our results shed new light on the insulating phases of organic quasi--1D compounds where the long--range part of the interaction is unscreened, and magnetic and charge orderings coexist at low temperatures.