Critical behavior of the three-dimensional +/- J Ising model at the paramagnetic-ferromagnetic transition line

We study the critical behavior of the three-dimensional +/- J Ising model [with random-exchange probability P(J(xy))=p delta(J(xy)-J)+(1-p)delta(J(xy)+J)] at the transition line between the paramagnetic and ferromagnetic phases, which extends from p=1 to a magnetic-glassy multicritical point at p=p(N)approximate to 0.768. By a finite-size scaling analysis of Monte Carlo simulations at various values of p in the region p(N)< p < 1, we provide strong numerical evidence that the critical behavior along the ferromagnetic transition line belongs to the same universality class as the three-dimensional randomly dilute Ising model. We obtain the results nu=0.682(3) and eta=0.036(2) for the critical exponents, which are consistent with the estimates nu=0.683(2) and eta=0.036(1) at the transition of randomly dilute Ising models.