I. J. L. Diaz, N. S. Branco
We study the critical behavior of a quenched random-exchange Ising model with
competing interactions on a bcc lattice. This model was introduced in the study
of the magnetic behavior of Fe_{1-x}Ru_x alloys for ruthenium concentrations
x=0%, x=4%, x=6%, and x=8%. Our study is carried out within a Monte Carlo
approach, with the aid of a re-weighting multiple histogram technique. By means
of a finite-size scaling analysis of several thermodynamic quantities, taking
into account up to the leading irrelevant scaling field term, we find estimates
of the critical exponents \alpha, \beta, \gamma, and \nu, and of the critical
temperatures of the model. Our results for x=0% are in excellent agreement with
those for the three-dimensional pure Ising model in the literature. We also
show that our critical exponent estimates for the disordered cases are
consistent with those reported for the transition line between paramagnetic and
ferromagnetic phases of both randomly dilute and $\pm J$ Ising models. We
compare the behavior of the magnetization as a function of temperature with
that obtained by Paduani and Branco (2008), qualitatively confirming the
mean-field result. However, the comparison of the critical temperatures
obtained in this work with experimental measurements suggest that the model
(initially obtained in a mean-field approach) needs to be modified.
View original:
http://arxiv.org/abs/1202.2104
No comments:
Post a Comment