Regensburg 1998 – scientific programme

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AM: Magnetismus

AM 11: Postersitzung

AM 11.5: Poster

Tuesday, March 24, 1998, 16:15–20:00, B

Relationship between degeneracy and structure of the ground states in frustrated ± J Ising systems — •S. Kobe², J.F. Valdés¹, J. Cartes¹, E.E. Vogel¹, and T. Klotz² — ¹Department of Physics, Universidad de La Frontera, Casilla 54-D, Temuco, Chile — ²Institut für Theoretische Physik, Technische Universität Dresden, 01062 Dresden, Germany

Ground states of Ising lattices with ± J exchange interactions are highly degenerated. Such degeneracy can be understood on the basis of ’local microcanonical ensembles (LEG’s)’. All states of a LEG, which are connected by single spin flips, are related to local groups or clusters of spins in the real space. For small L × L samples all ground states are calculated by exact optimization algorithms. Then the LEG’s are studied. Finally, the number of states associated to a cluster of alternating spins and its dependence on the size, the shape and the topology of the cluster and its surrounding plaquettes are analyzed. The dependence on the size of the systems is discussed.