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arXiv · 2103.01878

Emergent Potts Order in a Coupled Hexatic-Nematic XY model

Victor Drouin-Touchette·Peter P. Orth·Piers Coleman·Premala Chandra·Tom C. Lubensky
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Abstract

Addressing the nature of an unexpected smectic-A' phase in liquid crystal 54COOBC films, we perform large scale Monte Carlo simulations of a coupled hexatic-nematic XY model. The resulting finite-temperature phase diagram reveals a small region with composite Potts $\mathbb{Z}_3$ order above the vortex binding transition; this phase is characterized by relative hexatic-nematic ordering though both variables are disordered. The system develops algebraic hexatic and nematic order only at a lower temperature. This multi-step melting scenario agrees well with the experimental observations of a sharp specific heat anomaly that emerges above the onset of hexatic positional order. We therefore propose that the smectic-A' phase is characterized by composite Potts order and bound-states of fractional vortices.

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Victor Drouin-Touchette, Peter P. Orth, Piers Coleman, Premala Chandra, Tom C. Lubensky. 2021-03-02. Emergent Potts Order in a Coupled Hexatic-Nematic XY model. https://doi.org/10.1103/physrevx.12.011043

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