Small clusters with Heisenberg antiferromagnetic exchange

We study small symmetrical clusters of magnetic ions with Heisenberg antiferromagnetic exchange interaction. We calculate the magnetization and the specific heat as functions of applied magnetic field at zero and non-zero temperature. Results are given for both classical and quantum systems. At zero temperature the classical systems undergo a series of transitions where the symmetry changes as a function of applied field. The quantum systems show similar features to Ising systems previously studied.

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