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High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal
Published on: October 31, 2019
Competing interactions, the renormalization group, and the isotropic-nematic phase transition
Daniel G Barci1, Daniel A Stariolo
1Departamento de Física Teórica, Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier 524, 20550-013, Rio de Janeiro, RJ, Brazil.
Physical Review Letters
|August 7, 2007
Summary
We investigated 2D systems with Ising symmetry and competing interactions. Repulsive quadrupole interactions lead to a stripe phase, while attractive ones cause an isotropic-nematic transition with a higher critical temperature.
Area of Science:
- Condensed Matter Physics
- Statistical Mechanics
Background:
- Two-dimensional (2D) systems exhibit complex behaviors due to competing interactions at different length scales.
- Ising symmetry is a fundamental property influencing phase transitions in many physical systems.
Purpose of the Study:
- To investigate the impact of relevant quartic interactions, specifically quadrupole interactions, on the phase transitions of 2D Ising systems.
- To analyze the influence of repulsive and attractive quadrupole interactions within the renormalization group framework and self-consistent Hartree approximation.
Main Methods:
- Renormalization group (RG) analysis to study the flow of interactions under scale changes.
- Self-consistent Hartree approximation to model the behavior of quadrupole interactions.
- Analysis of phase transitions, including order and critical temperature.
Main Results:
- Repulsive quadrupole interactions drive a first-order phase transition to a stripe phase, consistent with the Brazovskii result.
- Attractive quadrupole interactions induce a second-order phase transition to an isotropic-nematic phase.
- The isotropic-nematic transition occurs at a higher critical temperature compared to the stripe phase.
Conclusions:
- Quadrupole interactions significantly alter the phase transition behavior in 2D Ising systems.
- The nature and critical temperature of phase transitions are sensitive to the sign of quadrupole interactions.
- This study provides insights into the rich phase diagrams of systems with competing interactions.
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