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

Article

关键词: VARIATIONAL WAVE-FUNCTIONS;    QUARTER-FILLED BAND;    ORGANIC CONDUCTORS;    MOTT TRANSITION;    GROUND-STATE;    WIGNER CRYSTAL;    GAS;    SALTS;    PHASE;    TCNQ;   

DOI  :  10.1103/PhysRevB.68.045112

来源: SCIE

【 摘 要 】

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 analyze 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.

【 授权许可】

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