arXiv subjects
Publications and source records attributed to M. D. Coutinho-Filho.
We present analytical and numerical results for the specific heat and susceptibility amplitude ratios in parallel plate geometries. The results are derived using field-theoretic techniques suitable to describe the system in the bulk limit. Advantages and drawbacks of our method are discussed on the light of other approaches previously reported in the literature.
The influence of a frustrated bond on the magnetic properties of a d=3 uniaxial (Ising) b.c.c. diluted antiferromagnet, with emphasis in the compound $Fe_{x}Zn_{1-x}F_{2}$, is investigated by a local mean-field numerical simulation. In particular we find that the initial drop of the saturation staggered magnetization ($M_{S}$) with concentration follows a percolation-like phenomenon characterized by an exponent $β_{p}$. For the frustrated samples, however, this regime is followed by a second one identified by a ``long tail" effect such that $M_{S}$ is zero only at the percolation threshold. Our numerical data also confirms a spin-glass phase near this threshold.
Using a microscopic numerical approach suitable to describe disordered antiferromagnets, with application to $Fe_{x}Zn_{1-x}F_{2}$, it is shown that the characteristics of the spin glass phase found for $x=0.25$ is much in agreement with the scenario predicted by the scaling theory of the droplet model.