Tricritical Behavior in Charge-Order System

Details Tricritical Behavior in Charge-Order System Tricritical Behavior in Charge-Order System

2006-05-27

arxiv.org/abs/cond-mat/0605675v1

J. Phys. Soc. Jpn. 75 (2006) 064705

Physics

Condensed Matter

Strongly Correlated Electrons

20 pages, 32 figures, to appear in J. Phys. Soc. Jpn. Vol.75(2006)No.6

Scientific paper

10.1143/JPSJ.75.064705

Tricritical point in charge-order systems and its criticality are studied for a microscopic model by using the mean-field approximation and exchange Monte Carlo method in the classical limit as well as by using the Hartree-Fock approximation for the quantum model. We study the extended Hubbard model and show that the tricritical point emerges as an endpoint of the first-order transition line between the disordered phase and the charge-ordered phase at finite temperatures. Strong divergences of several fluctuations at zero wavenumber are found and analyzed around the tricritical point. Especially, the charge susceptibility chi_c and the susceptibility of the next-nearest-neighbor correlation chi_R are shown to diverge and their critical exponents are derived to be the same as the criticality of the susceptibility of the double occupancy chi_D0. The singularity of conductivity at the tricritical point is clarified. We show that the singularity of the conductivity sigma is governed by that of the carrier density and is given as |sigma-sigma_c|=|g-g_c|^{p_t}Alog{|g-g_{c}|}+B), where g is the effective interaction of the Hubbard model, sigma_c g_c represents the critical conductivity(interaction) and A and B are constants, respectively. Here, in the canonical ensemble, we obtain p_t=2beta_t=1/2 at the tricritical point. We also show that p_t changes into p_{t}'=2beta=1 at the tricritical point in the grand-canonical ensemble when the tricritical point in the canonical ensemble is involved within the phase separation region. The results are compared with available experimental results of organic conductor (DI-DCNQI)2Ag.

Affiliated with

Also associated with

No associations

Rating

Tricritical Behavior in Charge-Order System does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Tricritical Behavior in Charge-Order System, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Tricritical Behavior in Charge-Order System will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-680449