Monte Carlo study of the critical behavior and magnetic properties of La2/3 Ca1/3MnO3 thin films

Critical exponents offer important information concerning the interaction mechanisms near the paramagnetic to ferromagnetic transition. In this work a Monte CarloMetropolis simulation of the critical behavior in La2/3Ca1/3MnO3 thin films is addressed. Canonical ensemble averages for magnetization per site, magnetic susceptibility and specific heat of stoichiometric manganite within a three-dimensional classical Heisenberg model with nearest magnetic neighbor interactions are computed. The La2/3Ca1/3MnO3 thin films were simulated addressing the thickness influence and thermal dependence. In the model, Mn magnetic ions are distributed on a simple cubic lattice according to the perovskite structure of this manganite. Ferromagnetic coupling for the bonds Mn3+Mn3+(e(g)e(g)'), Mn3+Mn4+(e(g)d(3)) and Mn3+Mn4+(e(g)'d(3)) were taken into account. On the basis of finite-size scaling theory, our best estimates of critical exponents, linked to the ferromagnetic to paramagnetic transition, for the correlation length, specific heat, magnetization and susceptibility are, respectively: nu=0.56 +/- 0.01, alpha=0.16 +/- 0.03, beta=0.34 +/- 0.04 gamma and gamma=1.17 +/- 0.05. These theoretical results are consistent with the Rushbrooke equalitiy alpha+2 beta+gamma=2. (C) 2010 Elsevier B.V. All rights reserved.