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Evidence of superstructures at low temperatures in frustrated spin systems

O'Hare A, Kusmartsev FV, Laad MS & Kugel KI (2006) Evidence of superstructures at low temperatures in frustrated spin systems, Physica C: Superconductivity and its Applications, 437-38, pp. 230-233.

We analyze the formation of stripe-like and droplet-like superstructures in a plane with classical magnetic moments forming a square lattice, which is relevant, in particular, to a two-dimensional array of π-rings. Each magnetic and orbital moment associated with a single π-ring is oriented perpendicular to the plane. We describe such arrays in the framework a two-dimensional Ising model with both nearest-neighbor and next-nearest-neighbor (diagonal) interactions. Such competing interactions introducing a strong frustration provide a plausible description for a dipole-dipole type of interaction. The model was studied with the use of several methods including exact diagonalization for small clusters, transfer matrix technique, as well as the Monte Carlo simulations for large lattices. The complete phase diagram resulting from this study includes, together with the conventional antiferromagnetic Ising and stripe phases, an additional glassy phase characterized by the formation of large-scale superstructures.

Ising model; dipole-dipole interaction; frustration; spin glass; pi-ring; transfer matrix; Monte Carlo simulations

AuthorsO'Hare Anthony, Kusmartsev Feodor V, Laad Mukul S, Kugel Kliment I
Publication date15/05/2006
ISSN 0921-4534

Physica c: Superconductivity and its Applications: Volume 437-38 (MAY 15 2006)

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