Chyh-Hong Chern, Naoto Nagaosa
Quantum melting of ferroelectric moment in the frustrated hydrogen-bonded system with "ice rule" is studied theoretically by using the quantum Monte Carlo simulation. The large number of nearly degenerate configurations are described as the gauge degrees of freedom, i.e., the model is mapped to a lattice gauge theory which shows the confinement-deconfinment transition (CDT). The dipole-dipole interaction $J_2$, on the other hand, explicitly breaks the gauge symmetry leading to the ferroelectric transition (FT). It is found that the crossover from FT to CDT manifests itself in the reduced correlation length of the polarization $\xi_{\text{FT}} \sim \Delta (K-K_c)^{-\nu}$ with $\Delta \propto \sqrt{J_2}$ while $K_c$ and $\nu$ remains finite in the limit $J_2 \to 0$. In contrast, the susceptibility $\chi$ and the spontaneous polarization continues smoothly in this limit. Moreover, CDT is related to the shape or volume of the molecules, and the its correlation length $\xi_{\text{CDT}}$ is not reduced in the limit of $J_2 \to 0$. A proposal for the neutron scattering or X-ray and Raman experiments is given to confirm this prediction.
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http://arxiv.org/abs/1301.4744
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