Critical behavior of repulsive dimers on square lattices at 2l3 monolayer coverage.-

F. ROMÁ; J. L. RICCARDO; A.J. RAMIREZ PASTOR

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Año: 2008 vol. 77 p. 195401 - 195409

1098-0121

Monte Carlo simulations and finite-size scaling theory have been used to study the critical behavior ofrepulsive dimers on square lattices at 2/3 monolayer coverage. A “zigzag” ZZ ordered phase, which ischaracterized by domains of parallel ZZ strips oriented at 45° from the lattice symmetry axes, was found. This ordered phase is separated from the disordered state by an order-disorder phase transition occurring at a finite critical temperature. Based on the strong axial anisotropy of the ZZ phase, an orientational order parameter has been introduced. All the critical quantities have been obtained. The set of critical exponents suggests that the system does not belong to the universality class of the two-dimensional Ising model.