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Phase transitions of the bilayered spin- S Heisenberg model

1996; American Physical Society; Volume: 53; Issue: 18 Linguagem: Inglês

10.1103/physrevb.53.12196

1095-3795

Kwai-Kong Ng, Fu‐Chun Zhang, Michael Ma,

Quantum many-body systems

We study the ground state and the phase transitions of the bilayered spin-S antiferromagnetic Heisenberg model using the Schwinger boson mean-field theory. The interplane coupling initially stabilizes but eventually destroys the long-range antiferromagnetic order. The transition to the disordered state is continuous for small S, and first order for large S. The latter is consistent with an argument based on spin-wave theory. \textcopyright{} 1996 The American Physical Society.