Article

# Monte Carlo study of the two-dimensional site-diluted dipolar Ising model

04/2010; DOI:doi:10.1103/PhysRevB.82.064425
Source: arXiv

ABSTRACT By tempered Monte Carlo simulations, we study 2D site-diluted dipolar Ising systems. Dipoles are randomly placed on a fraction x of all L^2 sites in a square lattice, and point along a common crystalline axis. For x_c< x<=1, where x_c = 0.79(5), we find an antiferromagnetic phase below a temperature which vanishes as x approaches x_c from above. At lower values of x, we study (i) distributions of the spin--glass (SG) overlap q, (ii) their relative mean square deviation Delta_q^2 and kurtosis and (iii) xi_L/L, where xi_L is a SG correlation length. From their variation with temperature and system size, we find that the paramagnetic phase covers the entire T>0 range. Our results enable us to obtain an estimate of the critical exponent associated to the correlation length at T=0, 1/nu=0.35(10). Comment: 10 LaTeX pages, 10 figures, 1 table.

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### Keywords

common crystalline axis

correlation length

entire T>0 range

kurtosis

L^2 sites

Monte Carlo simulations

paramagnetic phase

SG correlation length

square deviation Delta_q^2

square lattice

x approaches x_c