scholarly journals MOMENTUM DISTRIBUTION OF ITINERANT ELECTRONS IN THE ONE-DIMENSIONAL FALICOV–KIMBALL MODEL

2003 ◽  
Vol 17 (27) ◽  
pp. 4897-4911 ◽  
Author(s):  
PAVOL FARKAŠOVSKÝ
Keyword(s):  
Momentum Distribution ◽  
Ground States ◽  
Local Maximum ◽  
Singular Behavior ◽  
Coulomb Interactions ◽  
Unusual Behavior ◽  
One Dimensional ◽  
Itinerant Electrons ◽  
Half Filling ◽  
The One

The momentum distribution nk of itinerant electrons in the one-dimensional Falicov–Kimball model is calculated for various ground-state phases. In particular, we examine the periodic phases with period two, three and four (that are ground-states for all Coulomb interactions) as well as the phase separated states (that are ground states for small Coulomb interactions). For all periodic phases examined the momentum distribution is a smooth function of k with no sign of any discontinuity or singular behavior at the Fermi surface k=kF. An unusual behavior of nk (a local maximum) is found at k=3kF for electron concentrations outside half-filling. For the phase separated ground states the momentum distribution nk exhibits discontinuity at k=k0<kF. This behavior is interpreted in terms of a Fermi liquid.

scholarly journals ORDERING FROM FRUSTRATION IN A STRONGLY CORRELATED ONE-DIMENSIONAL SYSTEM

2009 ◽  
Vol 23 (18) ◽  
pp. 3687-3708
Author(s):  
SIDDHARTHA LAL ◽  
MUKUL S. LAAD
Keyword(s):  
Phase Diagram ◽  
Quantum Critical Point ◽  
Ground States ◽  
Charge Order ◽  
Dimensional System ◽  
Dimensional Crossover ◽  
Coulomb Interactions ◽  
One Dimensional ◽  
Spin Order ◽  
Quantum Critical

We study a one-dimensional extended Hubbard model with longer-range Coulomb interactions at quarter-filling in the strong coupling limit. We find two different charge-ordered (CO) ground states (Wigner and Peierls) as the strength of the longer range interactions is varied. At lower energies, the two CO states drive different spin-ordered ground states (Heisenberg antiferromagnet and dimerised respectively), reminiscent of the phase diagram of the TMTTF and TMTSF organic charge transfer salts. Several response functions computed in the quantum critical regime bear a remarkable resemblance to recent experimental observations related to CO in the organic TMTTF systems. RPA studies of coupled chains reveal a phase diagram with the ordered phase extended to finite temperatures and a phase boundary ending at a quantum critical point (QCP). Critical quantum fluctuations at the QCP enhance the transverse dispersion, leading to a dimensional crossover and a T = 0 deconfinement transition from insulating chains to anisotropic metallic planar behavior. Numerical estimates for the hierarchy of energy scales associated with charge and spin order and the dimensional crossover compare well with the values obtained experimentally. This leads us to propose that the TMTTF and TMTSF systems are proximate to a QCP associated with T = 0 charge order.

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