A Possible Phase Transition in beta-pyrochlore Compounds

Kazumasa Hattori; Hirokazu Tsunetsugu

doi:10.1143/jpsj.78.013603

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arXiv · 0809.0732

A Possible Phase Transition in beta-pyrochlore Compounds

Kazumasa Hattori·Hirokazu Tsunetsugu

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Abstract

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_2O_6(A=K, Rb or Cs). We obtain the first order phase transition line from large to small oscillation amplitude phases as temperature decreases. We also discuss the possibility of a phase with local electric polarizations. Our theory can explain the origin of the mysterious first order transition in KOs_2O_6.

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Kazumasa Hattori, Hirokazu Tsunetsugu. 2008-09-04. A Possible Phase Transition in beta-pyrochlore Compounds. https://doi.org/10.1143/jpsj.78.013603

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