科研之友
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摘要
We investigate a lattice of interacting anharmonic oscillators by using a mean field theory and exact diagonalization. We construct an effective five-state hopping model with intersite repulsions as a model for beta-pyrochlore AOs(2)O(6) (A = K, Rb or Cs). We find the line of the first order phase transition from large to small oscillation amplitude phases as temperature decreases. Our theory can explain the origin of the mysterious first order transition in KOs2O6. We also discuss the possibility of a phase with local electric polarizations.
- 出版日期2009-1
