STUDY OF AN ISING-MODEL WITH COMPETING LONG-RANGE AND SHORT-RANGE INTERACTIONS

A classical spin-one lattice gas model is used to study the competitio n between short-range ferromagnetic coupling and long-range antiferrom agnetic Coulomb interactions. The model is a coarse-grained representa tion of frustrated phase seapration in high-temperature superconductor s. The ground states are determined for the complete range of paramete rs by using a combination of numerical and analytical techniques. The crossover between ferromagnetic and antiferromagnetic states proceeds via a rich structure of highly symmetric striped and checkerboard phas es. There is no devil's staircase behavior because mixtures of stripes with different period phase separate.