In this study we present Monte Carlo simulations for a random-exchange mixed-spin Ising magnet. The case study consists of a mixed-spin oxide containing Fe(II) and Fe(III) with spins 4/2 and 5/2, respectively. Simulations were performed at $T=0$ for a layered $R\overline{3}$ structure, with 0, 33, and 57$\%$ Fe(III) and for 50, 75, and 100$\%$ ferromagnetic bonds. The simulated magnetization loops exhibit transition-like magnetization jumps upon field reversal. Comparison between spin-mixing composition and FM/AFM ratios provides insight into the partitioning of the magnetic structure into virtual clusters. The features of these clusters are directly dependent on percolation effects, where the mixing parameters determine the density of the partitioning fronts and can be assessed by the number of transitions during simulated field-sweep magnetization loops.

• Received 29 August 2011

DOI:https://doi.org/10.1103/PhysRevB.84.224434