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arXiv · 1105.4247

Quantum Monte Carlo study of the formation of molecular polarizations and the antiferroelectric ordering in squaric acid crystals

Hiroaki Ishizuka·Yukitoshi Motome·Nobuo Furukawa·Sei Suzuki
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Abstract

Effects of geometrical frustration and quantum fluctuation are theoretically investigated for the proton ordering in a quasi-two-dimensional hydrogen-bonded system, squaric acid crystal. We elucidate the phase diagram for an effective model, the transverse-field Ising model on a frustrated checkerboard lattice, by using quantum Monte Carlo simulation. A crossover to liquidlike paraelectric state with well-developed molecular polarizations is identified, distinguishably from long-range ordering. Emergence of long-range order from the liquidlike state exhibits peculiar aspects originating from the lifting of quasi-macroscopic degeneracy, such as colossal enhancement of the transition temperature and a vanishingly small anomaly in the specific heat.

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Hiroaki Ishizuka, Yukitoshi Motome, Nobuo Furukawa, Sei Suzuki. 2011-05-21. Quantum Monte Carlo study of the formation of molecular polarizations and the antiferroelectric ordering in squaric acid crystals. https://doi.org/10.1103/physrevb.84.064120

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