  The antiferromagnetic Ising model in small-world networks generated from
two-dimensional regular lattices has been studied. The disorder introduced by
long-range connections causes frustration, which gives rise to a spin-glass
phase at low temperature. Monte Carlo simulations have been carried out to
study the paramagnetic to spin-glass transition, as a function of the rewiring
probability p, which measures the disorder strength. The transition temperature
Tc goes down for increasing disorder, and saturates to a value Tc ~ 1.7 J for p
> 0.4, J being the antiferromagnetic coupling. For small p and at low
temperature, the energy increases linearly with p. In the strong-disorder limit
p=1, this model is equivalent to a short-range +-J spin glass in random
networks.
