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Updated: May 15, 2026
06:26
Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets
Published on: May 15, 2017
Re-orientation transition in molecular thin films: Potts model with dipolar interaction.
Danh-Tai Hoang1, Maciej Kasperski, Henryk Puszkarski
1Laboratoire de Physique Théorique et Modélisation, Université de Cergy-Pontoise, CNRS, UMR 8089 2, Avenue Adolphe Chauvin, F-95302 Cergy-Pontoise Cedex, France. danh-tai.hoang@u-cergy.fr
Summary
This study uses Monte Carlo simulations to investigate thin film phase transitions. We found that surface molecular ordering can transition from in-plane to perpendicular as temperature increases, influenced by anisotropy and dipolar interactions.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Statistical Mechanics
Background:
- Thin films exhibit complex low-temperature behavior and phase transitions.
- Understanding molecular orientation is crucial for thin film properties.
- Potts models are used to describe systems with discrete orientations.
Purpose of the Study:
- To investigate the low-temperature behavior and phase transitions of a thin film.
- To analyze the influence of dipolar interactions, anisotropy, and surface exchange on molecular ordering.
- To compare simulation results with experimental data from Fe/Gd.
Main Methods:
- Monte Carlo simulations on a simple cubic lattice.
- Modeling a three-state Potts model with specific Hamiltonian terms.
- Analyzing the effects of varying dipolar interaction strength (D), anisotropy (A), cutoff distance (r(c)), and surface exchange (J(s)).
Main Results:
- The ground state configuration is dependent on the ratio D/A and r(c).
- A re-orientation transition from in-plane to perpendicular ordering occurs with increasing temperature, below the paramagnetic phase transition.
- Surface phase transitions can occur before or after bulk transitions, depending on the J(s)/J ratio.
Conclusions:
- The interplay of dipolar interactions and anisotropy dictates the ground-state molecular orientation in thin films.
- A distinct re-orientation transition exists in these systems.
- Simulation results provide insights comparable to experimental observations in magnetic thin films.
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